Display device and sound providing method

ABSTRACT

A display device includes: a display panel; a first sound generator on a first surface of the display panel, the first sound generator being configured to vibrate the display panel to output a first sound; and a second sound generator configured to output a second sound. A third sound is a sum of the first sound and the second sound, and a sound pressure level of at least one of harmonic tones of the third sound is less than a sound pressure level of at least one of harmonic tones of the first sound.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean PatentApplication No. 10-2019-0072596, filed on Jun. 19, 2019 in the KoreanIntellectual Property Office (KIPO), the entire content of which isincorporated herein by reference.

BACKGROUND 1. Field

Exemplary embodiments/implementations of the present invention relategenerally to a display device and a sound providing method.

2. Description of the Related Art

With the development of information society, requirements for displaydevices for displaying images have increased in various forms. Forexample, display devices are applied to various electronic appliancessuch as smart phones, digital cameras, notebook computers, navigators,and smart televisions. A display device may include a display panel fordisplaying an image and a sound generator for providing a sound.

The sound output by the sound generator includes a fundamental tone anda harmonic tone. The harmonic tone refers to an overtone having afrequency that is an integer multiple of the frequency of thefundamental tone. The harmonic tone having a frequency that is an eveninteger multiple of the frequency of the fundamental tone may have thesame tone as the fundamental tone, but the harmonic tone having afrequency that is an odd integer multiple of the frequency of thefundamental tone may have a different tone from the fundamental tone.Due to the harmonic tone having a different tone from the fundamentaltone, sound quality may be deteriorated.

The above information disclosed in this Background section is only forunderstanding of the background of the inventive concepts, and,therefore, it may contain information that does not constitute priorart.

SUMMARY

Aspects of devices constructed according to exemplary implementations ofthe present invention are directed toward a display device, which canprevent or reduce the deterioration of sound quality due to a harmonictone having a different tone from a fundamental tone.

Aspects of methods constructed according to exemplary implementations ofthe present invention are directed toward a sound providing method ofthe display device, which can prevent or reduce the deterioration ofsound quality due to a harmonic tone having a different tone from afundamental tone.

Additional features of the inventive concepts will be set forth in thedescription which follows, and in part will be apparent from thedescription, or may be learned by practice of the inventive concepts.

According to one or more embodiments of the invention, a display deviceincludes: a display panel; a first sound generator on a first surface ofthe display panel, the first sound generator configured to vibrate thedisplay panel to output a first sound; and a second sound generatorbeing configured to output a second sound. A third sound is a sum of thefirst sound and the second sound, and a sound pressure level of at leastone of harmonic tones of the third sound is lower than a sound pressurelevel of at least one of harmonic tones of the first sound.

A difference between a phase of at least one of the harmonic tones ofthe first sound and a phase of at least one of harmonic tones of thesecond sound may be less than −90° and more than 90°.

The sound pressure level of at least one harmonic tone of the firstsound may be different from the sound pressure level of at least oneharmonic tone of the second sound.

A sound pressure level of a fundamental tone of the third sound may begreater than a sound pressure level of a fundamental tone of the firstsound.

A difference between a phase of the fundamental tone of the first soundand a phase of the fundamental tone of the second sound may be in arange from −90° to 90°.

The sound pressure level of the fundamental tone of the first sound maybe different from the sound pressure level of the fundamental tone ofthe second sound.

The sound pressure level of a first harmonic tone of the third sound maybe less than the sound pressure level of a first harmonic tone of thefirst sound, and the sound pressure level of a second harmonic tone ofthe third sound may be less than the sound pressure level of a secondharmonic tone of the first sound.

A difference between a phase of the first harmonic tone of the firstsound and a phase of the first harmonic tone of the second sound may beless than −90° and more than 90°, and a difference between a phase ofthe second harmonic tone of the first sound and a phase of the secondharmonic tone of the second sound may be less than −90° and more than90°.

The sound pressure level of the first harmonic tone of the first soundmay be different from the sound pressure level of the first harmonictone of the second sound, and the sound pressure level of the secondharmonic tone of the first sound may be different from the soundpressure level of the second harmonic tone of the second sound.

The sound pressure level of a first harmonic tone of the third sound maybe greater than the sound pressure level of a first harmonic tone of thefirst sound.

A difference between a phase of the first harmonic tone of the firstsound and a phase of the first harmonic tone of the second sound may bein a range from −90° to 90°.

The sound pressure level of a second harmonic tone of the third soundmay be less than the sound pressure level of a second harmonic tone ofthe first sound.

A difference between a phase of the second harmonic tone of the firstsound and a phase of the second harmonic tone of the second sound may beless than −90° and more than 90°.

Each of the first sound generator and the second sound generator may bea piezoelectric element or a piezoelectric actuator including apiezoelectric material configured to contract and to expand according toan applied voltage.

The second sound generator may be on the first surface of the displaypanel, and is configured to vibrate the display panel to output thesecond sound.

The display device may further include: a bracket on the first surfaceof the display panel. The second sound generator may be on a secondsurface of the bracket, facing the first surface of the display panel,and configured to vibrate the display panel to output the second sound.

The first sound generator may be a piezoelectric element or apiezoelectric actuator including a piezoelectric material configured tocontract and expand according to an applied voltage, and the secondsound generator may be a linear resonant actuator configured to vibratethe bracket by generating a magnetic force using a voice coil accordingto an applied voltage.

The display device may further include: a first sound driver may beconfigured to convert first sound data into first sound signals and tooutput the first sound signals to the first sound generator; a secondsound driver configured to convert second sound data into second soundsignals and to output the second sound signals to the second soundgenerator; and a phase shifter configured to modulate second sound dataand to output the second sound data to the second sound driver to shifta phase of a fundamental tone of the second sound and a phase of atleast one harmonic tone of the second sound.

The display device may further include: a main processor configured tooutput the first sound data to the first sound driver and output thesecond sound data to the phase shifter; and a main circuit board withthe main processor, the second sound driver, and the phase shifter.

The display device may further include: a display circuit board on thefirst surface of the display panel, the first sound driver being locatedon the display circuit board.

The phase shifter and the first sound driver may be formed as oneintegrated circuit.

The display device may further include: a first sound driver configuredto convert first sound data into first sound signals and to output thefirst sound signals to the first sound generator; a second sound driverconfigured to convert second sound data into second sound signals and tooutput the second sound signals to the second sound generator; and alook-up table configured to store information about a fundamental toneand at least one harmonic tone of the second sound according tofrequencies of a fundamental tone and at least one harmonic tone of thefirst sound.

The display device may further include: a main processor configured tooutput the first sound data to the first sound driver and to output thesecond sound data to a phase shifter; and a main circuit board with themain processor, the second sound driver, and the look-up table.

According to one or more embodiments of the invention, a sound provingmethod of a display device includes: shifting a phase of a fundamentaltone of a first sound in a first sound mode to generate a fundamentaltone of a second sound; shifting a phase of at least one harmonic toneof the first sound in the first sound mode to generate at least oneharmonic tone of the second sound; outputting first sound data includinginformation about the fundamental tone of the first sound and the atleast one harmonic tone of the first sound in the first sound mode, andoutputting second sound data including information about the fundamentaltone of the second sound and the at least one harmonic tone of thesecond sound in the first sound mode; generating first sound signalsaccording to the first sound data and outputting the first sound signalsto a first sound generator; and generating second sound signalsaccording to the second sound data and outputting the second soundsignals to a second sound generator.

The method may further include: shifting a phase of any one harmonictone of the second sound, having the same frequency as the fundamentaltone of the first sound, in a second sound mode; and outputting secondsound data including information about the fundamental tone of thesecond sound and the any one phase-shifted harmonic tone of the secondsound in the second sound mode.

The method may further include: shifting a phase of any one harmonictone of the second sound, having the same frequency as the fundamentaltone of the first sound, in a second sound mode; shifting a phase ofanother harmonic tone of the second sound, having the same frequency asthe any one harmonic tone of the first sound, in the second sound mode;and outputting second sound data including information about thefundamental tone of the second sound, the any one phase-shifted harmonictone of the second sound, and the another harmonic tone of the secondsound in the second mode.

A third sound may be a sum of the first sound and the second sound, anda sound pressure level of at least one of harmonic tones of the thirdsound may be less than a sound pressure level of at least one ofharmonic tones of the first sound.

According to aspects of the aforementioned and other exemplaryembodiments of the present disclosure, an amplification effect that thesound pressure level of the fundamental tone of the third sound, whichis a sum of the first sound and the second sound, becomes higher thanthe sound pressure level of the fundamental tone of the first sound canbe obtained, and concurrently (e.g., simultaneously) an offset effectthat the sound pressure level of at least one of the harmonic tones ofthe third sound becomes lower than (or less than) the sound pressurelevel of any one of the harmonic tones of the first sound can beobtained. Therefore, it is possible to prevent or reduce thedeterioration of sound quality provided to the user due to the harmonictones of the first sound and to provide a high-quality sound byincreasing the sound pressure level of the fundamental tone of the firstsound.

Further, an offset effect that the sound pressure levels of the harmonictones each having a different tone from the fundamental tone of thefirst sound become low can be obtained, and concurrently (e.g.,simultaneously) an amplification effect that the sound pressure levelsof the harmonic tones each having the same tone as the fundamental toneof the first sound become high can be obtained. Therefore, it ispossible to prevent or reduce the deterioration of sound qualityprovided to the user due to the harmonic tones each having a differenttone from the fundamental tone of the first sound and to provide ahigh-quality sound by increasing the sound pressure levels of theharmonic tones each having the same tone as the fundamental tone of thefirst sound.

Other features and exemplary embodiments may be apparent from thefollowing detailed description, the drawings, and the claims.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate exemplary embodiments of theinvention, and together with the description serve to explain theinventive concepts.

FIG. 1 is a perspective view of a display device according to anexemplary embodiment.

FIG. 2 is an exploded perspective view of a display device according toan exemplary embodiment.

FIG. 3 is a bottom view showing a display panel attached to the coverwindow of FIG. 2 according to an exemplary embodiment.

FIG. 4 is a bottom view showing a bracket attached to the lower surfaceof the display panel of FIG. 3 and a main circuit board disposed on thebracket according to an exemplary embodiment.

FIG. 5 is a cross-sectional view taken along the line I-I′ of FIG. 3according to an exemplary embodiment.

FIG. 6 is a cross-sectional view specifically showing the display areaof the display panel of FIG. 5 according to an exemplary embodiment.

FIG. 7 is a cross-sectional view specifically showing the first soundgenerator of FIG. 5 according to an exemplary embodiment.

FIG. 8 is a view showing a method of vibrating a vibration layerdisposed between the first branch electrode and second branch electrodeof the first sound generator of FIG. 7 according to an exemplaryembodiment.

FIG. 9 is a perspective view specifically showing the second soundgenerator of FIG. 5 according to an exemplary embodiment.

FIG. 10 is a flowchart showing a sound providing method of a displaydevice according to an exemplary embodiment.

FIGS. 11-13 are graphs showing the sound pressure level of a first sounddepending on a fundamental tone and harmonic tone according to anexemplary embodiment, the sound pressure level of a second sounddepending on a fundamental tone and harmonic tone according to anexemplary embodiment, and the sound pressure level of a third sound,which is a sum of the first sound and the second sound, depending on afundamental tone and harmonic tone according to an exemplary embodiment.

FIG. 14 is a waveform diagram showing the amplitudes of the fundamentaltone of a first sound and the fundamental tone of a second sounddepending on time according to an exemplary embodiment.

FIG. 15 is a view showing the phase and amplitude of a first sound, thephase and amplitude of a second sound, and the phase and amplitude of athird sound according to an exemplary embodiment.

FIG. 16 is a waveform diagram showing the amplitudes of the firstharmonic tone of a first sound and the first harmonic tone of a secondsound depending on time according to an exemplary embodiment.

FIG. 17 is a view showing the phase and amplitude of a first sound, thephase and amplitude of a second sound, and the phase and amplitude of athird sound according to an exemplary embodiment.

FIG. 18 is a view showing the first frequency band of a first sound, thesecond frequency band of a second sound, and the third frequency bandwhich is a frequency band overlapping the first frequency band and thesecond frequency band according to an exemplary embodiment.

FIG. 19 is a flowchart showing a sound providing method of a displaydevice according to another embodiment according to an exemplaryembodiment.

FIGS. 20-22 are graphs showing the sound pressure level and phase of afirst sound depending on a frequency according to an exemplaryembodiment, the sound pressure level and phase of a second sounddepending on a frequency according to an exemplary embodiment, and thesound pressure level and of a third sound, which is a sum of the firstsound and the second sound, depending on a frequency according to anexemplary embodiment.

FIG. 23 is a bottom view showing a bracket attached to the lower surfaceof the display panel of FIG. 3 and a main circuit board disposed on thebracket according to an exemplary embodiment.

FIG. 24 is a bottom view showing a display panel attached to the coverwindow of FIG. 2 according to an exemplary embodiment.

FIG. 25 is a bottom view showing a bracket attached to the lower surfaceof the display panel of FIG. 3 and a main circuit board disposed on thebracket according to an exemplary embodiment.

DETAILED DESCRIPTION

In the following description, for the purposes of explanation, numerousspecific details are set forth in order to provide a thoroughunderstanding of various exemplary embodiments or implementations of theinvention. As used herein “embodiments” and “implementations” areinterchangeable words that are non-limiting examples of devices ormethods employing one or more of the inventive concepts disclosedherein. It is apparent, however, that various exemplary embodiments maybe practiced without these specific details or with one or moreequivalent arrangements. In other instances, well-known structures anddevices are shown in block diagram form in order to avoid unnecessarilyobscuring various exemplary embodiments. Further, various exemplaryembodiments may be different, but do not have to be exclusive. Forexample, specific shapes, configurations, and characteristics of anexemplary embodiment may be used or implemented in another exemplaryembodiment without departing from the inventive concepts. Also, the term“exemplary” is intended to refer to an example or illustration.

Unless otherwise specified, the illustrated exemplary embodiments are tobe understood as providing exemplary features of varying detail of someways in which the inventive concepts may be implemented in practice.Therefore, unless otherwise specified, the features, components,modules, layers, films, panels, regions, and/or aspects, etc.(hereinafter individually or collectively referred to as “elements”), ofthe various embodiments may be otherwise combined, separated,interchanged, and/or rearranged without departing from the inventiveconcepts.

The use of cross-hatching and/or shading in the accompanying drawings isgenerally provided to clarify boundaries between adjacent elements. Assuch, neither the presence nor the absence of cross-hatching or shadingconveys or indicates any preference or requirement for particularmaterials, material properties, dimensions, proportions, commonalitiesbetween illustrated elements, and/or any other characteristic,attribute, property, etc., of the elements, unless specified. Further,in the accompanying drawings, the size and relative sizes of elementsmay be exaggerated for clarity and/or descriptive purposes. When anexemplary embodiment may be implemented differently, a specific processorder may be performed differently from the described order. Forexample, two consecutively described processes may be performedsubstantially at the same time or performed in an order opposite to thedescribed order. Also, like reference numerals denote like elements.

When an element, such as a layer, is referred to as being “on,”“connected to,” or “coupled to” another element or layer, it may bedirectly on, connected to, or coupled to the other element or layer orintervening elements or layers may be present. When, however, an elementor layer is referred to as being “directly on,” “directly connected to,”or “directly coupled to” another element or layer, there are nointervening elements or layers present. To this end, the term“connected” may refer to physical, electrical, and/or fluid connection,with or without intervening elements. As used herein, the terms “use,”“using,” and “used” may be considered synonymous with the terms“utilize,” “utilizing,” and “utilized,” respectively. Further, theX-axis, the Y-axis, and the Z-axis are not limited to three axes of arectangular coordinate system, such as the x, y, and z axes, and may beinterpreted in a broader sense. For example, the X-axis, the Y-axis, andthe Z-axis may be perpendicular to one another, or may representdifferent directions that are not perpendicular to one another. For thepurposes of this disclosure, “at least one of X, Y, and Z” and “at leastone selected from the group consisting of X, Y, and Z” may be construedas X only, Y only, Z only, or any combination of two or more of X, Y,and Z, such as, for instance, XYZ, XYY, YZ, and ZZ. As used herein, theterm “and/or” includes any and all combinations of one or more of theassociated listed items.

Although the terms “first,” “second,” etc. may be used herein todescribe various types of elements, these elements should not be limitedby these terms. These terms are used to distinguish one element fromanother element. Thus, a first element discussed below could be termed asecond element without departing from the teachings of the disclosure.

Spatially relative terms, such as “beneath,” “below,” “under,” “lower,”“above,” “upper,” “over,” “higher,” “side” (e.g., as in “sidewall”), andthe like, may be used herein for descriptive purposes, and, thereby, todescribe one elements relationship to another element(s) as illustratedin the drawings. Spatially relative terms are intended to encompassdifferent orientations of an apparatus in use, operation, and/ormanufacture in addition to the orientation depicted in the drawings. Forexample, if the apparatus in the drawings is turned over, elementsdescribed as “below” or “beneath” other elements or features would thenbe oriented “above” the other elements or features. Thus, the exemplaryterm “below” can encompass both an orientation of above and below.Furthermore, the apparatus may be otherwise oriented (e.g., rotated 90degrees or at other orientations), and, as such, the spatially relativedescriptors used herein interpreted accordingly.

The terminology used herein is for the purpose of describing particularembodiments and is not intended to be limiting. As used herein, thesingular forms, “a,” “an,” and “the” are intended to include the pluralforms as well, unless the context clearly indicates otherwise. Moreover,the terms “comprises,” “comprising,” “includes,” and/or “including,”when used in this specification, specify the presence of statedfeatures, integers, steps, acts, operations, elements, components,and/or groups thereof, but do not preclude the presence or addition ofone or more other features, integers, steps, acts, operations, elements,components, and/or groups thereof. It is also noted that, as usedherein, the terms “substantially,” “about,” and other similar terms, areused as terms of approximation and not as terms of degree, and, as such,are utilized to account for inherent deviations in measured, calculated,and/or provided values that would be recognized by one of ordinary skillin the art.

Various exemplary embodiments are described herein with reference tosectional and/or exploded illustrations that are schematic illustrationsof idealized exemplary embodiments and/or intermediate structures. Assuch, variations from the shapes of the illustrations as a result, forexample, of manufacturing techniques and/or tolerances, are to beexpected. Thus, exemplary embodiments disclosed herein should notnecessarily be construed as limited to the particular illustrated shapesof regions, but are to include deviations in shapes that result from,for instance, manufacturing. In this manner, regions illustrated in thedrawings may be schematic in nature and the shapes of these regions maynot reflect actual shapes of regions of a device and, as such, are notnecessarily intended to be limiting.

As is customary in the field, some exemplary embodiments are describedand illustrated in the accompanying drawings in terms of functionalblocks, units, and/or modules. Those skilled in the art will appreciatethat these blocks, units, and/or modules are physically implemented byelectronic (or optical) circuits, such as logic circuits, discretecomponents, microprocessors, hard-wired circuits, memory elements,wiring connections, and the like, which may be formed usingsemiconductor-based fabrication techniques or other manufacturingtechnologies. In the case of the blocks, units, and/or modules beingimplemented by microprocessors or other similar hardware, they may beprogrammed and controlled using software (e.g., microcode) to performvarious functions discussed herein and may optionally be driven byfirmware and/or software. It is also contemplated that each block, unit,and/or module may be implemented by dedicated hardware, or as acombination of dedicated hardware to perform some functions and aprocessor (e.g., one or more programmed microprocessors and associatedcircuitry) to perform other functions. Also, each block, unit, and/ormodule of some exemplary embodiments may be physically separated intotwo or more interacting and discrete blocks, units, and/or moduleswithout departing from the scope of the inventive concepts. Further, theblocks, units, and/or modules of some exemplary embodiments may bephysically combined into more complex blocks, units, and/or moduleswithout departing from the scope of the inventive concepts.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this disclosure is a part. Terms,such as those defined in commonly used dictionaries, should beinterpreted as having a meaning that is consistent with their meaning inthe context of the relevant art and should not be interpreted in anidealized or overly formal sense, unless expressly so defined herein.

FIG. 1 is a perspective view of a display device according to anexemplary embodiment, and FIG. 2 is an exploded perspective view of adisplay device according to an exemplary embodiment.

Referring to FIGS. 1 and 2, a display device 10 according to anexemplary embodiment includes a cover window 100, a display panel 300, adisplay circuit board 310, a display driving circuit 320, a flexiblefilm 390, a first sound generator 510, a second sound generator 520, abracket 600, a main circuit board 700, and a lower cover 900.

The terms “on”, “over”, “top”, “upper side”, or “upper surface” refersto a direction in which the cover window 100 is disposed with respect tothe display panel 300 (i.e., a Z-axis direction), and the terms“beneath”, “under”, “bottom”, or “lower surface” refer to a direction inwhich the bracket 600 is disposed with respect to the display panel 300(i.e., a direction opposite to the Z-axis direction). Further, the terms“left”, “right”, “upper”, and “lower” refer to directions when thedisplay panel 300 is viewed from a plan view (e.g., in a plane parallelto an X-Y plane of FIGS. 1 and 2). For example, the term “left” refersto a direction opposite to the X-axis direction, the term “right” refersto the X-axis direction, the term “upper” refers to the Y-axisdirection, and the “lower” refers to a direction opposite to the Y-axisdirection.

The display device 10 may have a rectangular shape in a plan view. Forexample, as shown in FIGS. 1 and 2, the display device 10 may have arectangular planar shape having short sides in the first direction(X-axis direction) and long sides in the second direction (Y-axisdirection). The edge where the short side in the first direction (X-axisdirection) meets the long side in the second direction (Y-axisdirection) may be formed to have a round shape of a predetermined or aset curvature or have a right angle shape. The planar shape of thedisplay device 10 is not limited to a rectangular shape, and may beformed in another polygonal shape, circular shape, or elliptical shape.

The display device 10 may include a first area DR1 formed flat and asecond area DR2 extending from the right and left sides of the firstarea DR1. The second area DR2 may be formed to be flat or be curved.When the second area DR2 is flat, the angle formed by the first area DR1and the second area DR2 may be an obtuse angle. In other words, theboundary of the first area DR1 and the second area DR2 may form anobtuse angle. When the second area DR2 is curved, the second area DR2may have a constant curvature or a variable curvature.

Although it is shown in FIG. 1 that the second area DR2 extends from theleft and right sides of the first area DR1, the present invention is notlimited thereto. For example, the second area DR2 may extend from onlyone of the left and right sides of the first area DR1. In addition, thesecond area DR2 may extend from only one of the upper and lower sides ofthe first area DR1 as well as only one of the left and right sides ofthe first area DR1. Hereinafter, it is assumed that the second area DR2is disposed along the left and right edges of the display device 10.

The cover window 100 may be disposed on the display panel 300 so as tocover the upper surface of the display panel 300. Thus, the cover window100 may function to protect the upper surface of the display panel 300.

The cover window 100 may include a light transmitting area DA100corresponding to the display panel 300 and a light blocking area NDA100corresponding to an area other than the display panel 300. The coverwindow 100 may be disposed in the first area DR1 and the second areaDR2, and the light transmitting area DA100 may be disposed in a part ofthe first area DR1 and a part of the second area DR2. The light blockingarea NDA100 may be formed to be opaque. In some embodiments, the lightblocking area NDA100 may be formed as a decorative layer having apattern that can be seen to a user when an image is not displayed.

The display panel 300 may be disposed under the cover window 100. Thedisplay panel 300 may be disposed to overlap the light transmitting area100DA of the cover window 100. The display panel 300 may be disposed inthe first area DR1 and the second areas DR2. Thus, the image of thedisplay panel 300 may be seen not only in the first area DR1 but also inthe second areas DR2.

The display panel 300 may be a light emitting display panel including alight emitting element. Examples of the display panel 300 may include anorganic light emitting display panel using an organic light emittingdiode including an organic light emitting layer, an ultra-micro lightemitting diode display panel using an ultra-micro light emitting diode(ultra-micro LED), a quantum dot light emitting diode display panelusing a quantum dot light emitting diode including a quantum dot lightemitting layer, and an inorganic light emitting display panel using aninorganic light emitting diode including an inorganic semiconductor.Hereinafter, it is assumed that the display panel 300 is an organiclight emitting display panel.

The display circuit board 310 and the display driving circuit 320 may beattached to one side of the display panel 300. One end of the displaycircuit board 310 may be attached to pads provided at (or on) one sideof the display panel 300 using an anisotropic conductive film. Thedisplay circuit board 310 may be a flexible printed circuit board, arigid printed circuit board that is not easily bent, or a compositeprinted circuit board including both the flexible printed circuit boardand the rigid printed circuit board.

The display driving circuit 320 receives control signals and powersupply voltages through the display circuit board 310. In someembodiments, the display driving circuit 320 generates and outputssignals and voltages for driving the display panel 300. The displaydriving circuit 320 may be formed as an integrated circuit and may beattached onto the display panel 300 using a chip on glass (COG) manner,a chip on plastic (COP) manner, or an ultrasonic manner, but the presentinvention is not limited thereto. For example, the display drivingcircuit 320 may be attached onto the display circuit board 310. A touchdriving circuit 330 and a first sound driver 340 may be disposed on thedisplay circuit board 310.

The touch driving circuit 330 may be formed as an integrated circuit andmay be attached to the upper surface of the display circuit board 310.The touch driving circuit 330 may be connected to the touch electrodesof a touch sensor layer of the display panel 300 through the displaycircuit board 310. The touch driving circuit 330 may apply touch drivingsignals to driving electrodes from among the touch electrodes, and maysense the charge variations of capacitances between the drivingelectrodes and the sensing electrodes through the sensing electrodesfrom among the touch electrodes, thereby outputting touch data includinga user's touch coordinates.

The first sound driver 340 receives first sound data from the maincircuit board 700. The first sound driver 340 generates first soundsignals according to the first sound data, and outputs the first soundsignals to the first sound generator 510. The first sound driver 340 maybe formed as an integrated circuit.

A power supply unit for supplying display driving voltages for drivingthe display driving circuit 320 may be disposed on the display circuitboard 310. The display driving voltages and the first sound signals mayinfluence each other when they are generated from one circuit. However,the display driving voltages for driving the display panel 300 and thefirst sound signals for driving the first sound generator 510 may begenerated from different circuits from each other. Therefore, it ispossible to substantially prevent or prevent the display drivingvoltages and the first sound signals from influencing each other.

One side of the flexible film 390 may be attached to the upper surfaceof the display panel 300 in the lower side of the display panel 300through an anisotropic conductive film. The other side of the flexiblefilm 390 may be attached to the upper surface of the display circuitboard 310 in the upper side of the display circuit board 310 through ananisotropic conductive film. The flexible film may be a film that can bebent.

Meanwhile, the flexible film 390 may be omitted, and the display circuitboard 310 may be directly attached to one side of the display panel 300.In this case, one side of the display panel 300 may be bent toward thelower surface of the display panel 300.

The first sound generator 510 may be disposed on one side of the displaypanel 300. As shown in FIG. 5, the first sound generator 510 may beattached on one side of the display panel 300 using a first adhesivemember 610 such as a pressure sensitive adhesive. As shown in FIGS. 3and 5, when a panel lower member 400 is disposed on one surface of thedisplay panel 300, the first sound generator 510 may be attached ontothe panel lower member 400 through the first adhesive member 610. Thefirst sound generator 510 may be a piezoelectric element or apiezoelectric actuator that vibrates the display panel 300 using apiezoelectric material contracting and expanding according to an appliedvoltage. Although it is illustrated in FIG. 2 that the first soundgenerator 510 has a rectangular parallelepiped shape, the shape of thefirst sound generator 510 is not limited thereto.

The bracket 600 may be disposed under the display panel 300. The bracket600 may include plastic, metal, or both plastic and metal. The bracket600 may be provided with a first camera hole CMH1 into which a cameradevice 720 is inserted, a battery hole BH in which a battery isdisposed, and a cable hole CAH through which a cable 314 connected tothe display circuit board 310 passes.

A second sound generator 520 may be disposed on one surface of thebracket 600. The second sound generator 520 may be a linear resonantactuator (LRA) that vibrates the bracket 600 by generating a magnetforce using a voice coil based on an applied voltage. Although it isillustrated in FIG. 2 that the second sound generator 520 has acylindrical shape, the shape of the second sound generator 520 is notlimited thereto.

When the first sound generator 510 is a piezoelectric element or apiezoelectric actuator and the second sound generator 520 is a linearresonant actuator (LRA), the first sound generator 510 is suitable foroutputting a sound of a relatively higher frequency band than the secondsound generator 520, and the second sound generator 520 is suitable foroutputting a sound of a relatively lower frequency band than the firstsound generator 510.

The main circuit board 700 and a battery 790 may be disposed under thebracket 600. The main circuit board 700 may be a printed circuit boardor a flexible printed circuit board.

The main circuit board 700 may include a main processor 710, a cameradevice 720, a main connector 730, a memory 740, a phase shifter 750, anda second sound driver 760. Each of the main processor 710, the phaseshifter 750, and the second sound driver 760 may be formed as anintegrated circuit.

The camera device 720 may be disposed on both the upper surface and thelower surface of the main circuit board 700. The main processor 710, thememory 740, the phase shifter 750, and the second sound driver 760 maybe disposed on the upper surface of the main circuit board 700, and themain connector 730 may be disposed on the lower surface of the maincircuit board 700. The phase shifter 750 may be disposed in the firstsound driver 340 without being disposed on the upper surface of the maincircuit board 700. That is, the first sound driver 340 and the phaseshifter 750 may be constituted by one integrated circuit.

The main processor 710 may control all the functions of the displaydevice 10. For example, the main processor 710 may output digital videodata to the display driving unit (e.g., display driving circuit 320)through the display circuit board 310 such that the display panel 300displays an image. Further, the main processor 710 may receive touchdata from the touch driving unit (e.g., touch driving circuit 330),determine the touch position of a user, and then execute an applicationindicated by an icon displayed at the touch position of the user.Further, the main processor 710 may receive touch data from the touchdriving unit 220, and may execute an application indicated by an icondisplayed at the touch coordinate of the user according to the touchdata.

The main processor 710 receives sound source data from the outside andoutputs the sound source data to the memory 740. Because the memory 740stores sound data according to the frequency of the sound source data,the memory 740 may output the sound data by using the frequency of thesound source data as an input address.

The main processor 710 may control the display device 10 in a firstsound mode and a second sound mode. In order to prevent thedeterioration of sound quality due to the harmonic tones of a firstsound, the main processor 710 may control the display device 10 so as tocancel or partially cancel at least one harmonic tone of the first soundoutput by the first sound generator 510 using at least one harmonic toneof the second sound output by the second sound generator 520 and toamplify the fundamental tone of the first sound using the fundamentaltone of the second sound. The main processor 710 may generate firstsound data according to the sound data input from the memory 740 in thefirst sound mode. The main processor 710 may output the first sound datato the phase shifter 750 in the first sound mode.

In order to provide a sound having both a low frequency band and a highfrequency band in the second sound mode, the main processor 710 maycontrol the display device 10 such that the first sound generator 510outputs a first sound of a high frequency band, and the second soundgenerator 520 outputs a second sound of a low frequency band. The mainprocessor 710 may generate first sound data and second sound dataaccording to the sound data input from the memory 740 in the secondsound mode. The main processor 710 may output the first sound data andthe second sound data to the phase shifter in the second sound mode.

The first sound data includes information about the frequency of afundamental tone of the first sound and the frequencies of harmonictones of the first sound and information about the sound pressure levelor amplitude of a fundamental tone of the first sound and the soundpressure levels or amplitudes of harmonic tones of the first sound. Thesecond sound data includes information about the frequency of afundamental tone of the second sound and the frequencies of harmonictones of the second sound and information about the sound pressure levelor amplitude of a fundamental tone of the second sound and the soundpressure levels or amplitudes of harmonic tones of the second sound.

The phase shifter 750 receives the first sound data in the first soundmode. The phase shifter 750 modulates the first sound data in the firstsound mode and outputs the second sound data. The phase shifter 750 mayshift the phase of a fundamental tone of the first sound and the phasesof harmonic tones of the first sound data to generate the fundamentaltone and harmonic tones of the second sound. The sound pressure levelsof the fundamental tone and harmonic tones of the third sound, which isa sum of the first sound and the second sound, may be higher or lowerthan (i.e., different from) the sound pressure levels of the fundamentaltone and harmonic tones of the first sound.

The phase shifter 750 receives the first sound data and the second sounddata in the second sound mode. The phase shifter 750 may modulate boththe first sound data and the second sound data in the second sound mode,or may modulate any one of the first sound data and the second sounddata in the second sound mode. The phase shifter 750 may output thefirst sound data to the first sound driver 340, and may output thesecond sound data to the second sound driver 760.

The phase shifter 750 may shift the phase of the harmonic tone of thesecond sound, having the same frequency as the fundamental tone of thefirst sound or any one of the harmonic tones of the first tone. Thus,the sound pressure level of the fundamental tone of the third sound orany one of the harmonic tones of the third sound, the third sound beinga sum of the first sound and the second sound, may be lower than (orless than) the sound pressure level of the fundamental tone of the firstsound or any one of the harmonic tones of the first sound.

As described above, due to the phase shifter 750, an amplificationeffect may occur that causes the sound pressure level of the fundamentaltone of the third sound, which is a sum of the first sound and thesecond sound, to become higher than (or greater than) the sound pressurelevel of the fundamental tone of the first sound, and concurrently(e.g., simultaneously) an offset effect may occur that causes the soundpressure level of any one of the harmonic tones of the third sound tobecome lower than (or less than) the sound pressure level of any one ofthe harmonic tones of the first sound. Therefore, it is possible toprevent or reduce the deterioration of sound quality provided to theuser due to the harmonic tones of the first sound.

The main processor 710 may be an application processor, a centralprocessing unit, or a system chip, which includes an integrated circuit.

The camera device 720 processes an image frame such as a still image ora moving image obtained by an image sensor in a camera mode, and outputsthe processed image frame to the main processor 710.

The cable 314 having passed through the cable hole CAH of the bracket600 may be connected to the main connector 730. Thus, the main circuitboard 700 may be electrically connected to the display circuit board310.

The second sound driver 760 receives the second sound data from thephase shifter 750. The second sound driver 760 generates second soundsignals according to the second sound data, and outputs the second soundsignals to the second sound generator 520.

In addition, the main circuit board 700 may be further provided with amobile communication module capable of transmitting and receiving aradio signal to/from at least one of a base station, an externalterminal, and a server. The radio signal may include various suitabletypes of data depending on a voice signal, a video call signal, or atext/multimedia message transmission/reception.

The battery 790 may be disposed not to overlap the main circuit board700 in the third direction (Z-axis direction). The battery 790 mayoverlap the battery hole BH of the bracket 600.

The lower cover 900 may be disposed under the main circuit board 700 andthe battery 790. The lower cover 900 may be engaged and fixed to thebracket 600. The lower cover 900 may form a lower surface appearance ofthe display device 10. The lower cover 900 may include plastic and/ormetal.

The lower cover 900 may be provided with a second camera hole CMH2through which the camera device 720 (e.g., a camera device 720 disposedon the lower surface of the main circuit board 700) is exposed. Theposition of the camera device 720 and the positions of the first andsecond camera holes CMH1 and CMH2 corresponding to the camera device 720are not limited to the embodiment shown in FIG. 2.

FIG. 3 is a bottom view showing a display panel attached to the coverwindow of FIG. 2 according to an exemplary embodiment, and FIG. 4 is abottom view showing a bracket 600 attached to the lower surface of thedisplay panel of FIG. 3 and a main circuit board 700 disposed on thebracket 600 according to an exemplary embodiment.

Referring to FIGS. 3 and 4, the panel lower member 400 (e.g., panellower cover) may be disposed under the display panel 300. The panellower member 400 (e.g., panel lower cover) may be attached to the lowersurface of the display panel 300 through an adhesive member. Theadhesive member may be a pressure sensitive adhesive (PSA).

The panel lower member 400 (e.g., panel lower cover) may include atleast one of a light absorbing member for absorbing light incident fromthe outside, a buffer member for absorbing external impact, and a heatradiation member for efficiently radiating heat of the display panel300.

The light absorbing member may be disposed under the display panel 300.The light absorbing member inhibits the transmission of light to preventor substantially prevent components disposed under the light absorbingmember (e.g., a display circuit board 310, a first sound generator 510,and the like) from being viewed or visible from above the display panel300. The light absorbing member may include a light absorbing materialsuch as a black pigment or a dye.

The buffer member may be disposed under the light absorbing member. Thebuffer member absorbs an external impact to substantially prevent orprevent the display panel 300 from being damaged. The buffer member maybe formed as a single layer or a plurality of layers. For example, thebuffer member may be formed of a polymer resin such as polyurethane,polycarbonate, polypropylene, and/or polyethylene, or may be formed ofan elastic material such as a rubber, a urethane material, and/or asponge formed by foaming an acrylic material. The buffer member may be acushion layer.

The heat radiation member may be disposed under the buffer member. Theheat radiation member may include a first heat radiation layer includinggraphite or carbon nanotubes and a second heat radiation layer capableof blocking electromagnetic waves and formed of a metal thin film ofcopper, nickel, ferrite and/or silver having excellent thermalconductivity.

Meanwhile, the panel lower member 400 may be omitted. In this case, thecomponents disposed on the lower surface of the panel lower member 400(e.g., the display circuit board 310, the first sound generator 510, andthe like) may be disposed on the lower surface of the display panel 300instead of the lower surface of the panel lower member 400.

The flexible film 390 attached to one side of the display panel 300 maybe bent (FIG. 3 shows the flexible film 390 already bent according to anexemplary embodiment), and may be disposed under the panel lower member400. Therefore, the display circuit board 310 attached to one side ofthe flexible film 390 may be disposed under the panel lower member 400.The display circuit board 310 may be fixed or attached to the lowersurface of the panel lower member 400 by a fixing member such as a screwor an adhesive member such as a pressure sensitive adhesive under thepanel lower member 400.

The display circuit board 310 may include a first circuit board 311 anda second circuit board 312. Each of the first circuit board 311 and thesecond circuit board 312 may be a rigid printed circuit board or aflexible printed circuit board. When any one of the first circuit board311 and the second circuit board 312 is a rigid printed circuit boardand the other one thereof is a flexible printed circuit board, thedisplay circuit board 310 may be a composite printed circuit board.

It is illustrated in FIG. 3 that the second circuit board 312 extendsfrom one side of the first circuit board 311 in the second direction(Y-axis direction). The width of the second circuit board 312 in thefirst direction (X-axis direction) may be smaller than the width of thefirst circuit board 311 in the first direction (X-axis direction).

The touch driving circuit 330 and the first sound driver 340 may bedisposed on one surface of the second circuit board 312, and a firstconnector 313 and a second connector 316 may be disposed on the othersurface (e.g., the opposite surface) of the second circuit board 312.The first connector 313 may include an insertion portion connected to afirst connection terminal provided at one end of the cable 314. Thesecond connector 316 may include an insertion portion connected to aconnection terminal provided at one end of a first flexible circuitboard 570.

The first connection terminal provided at one end of the cable 314 maybe inserted into the insertion portion of the first connector 313. Thesecond connection terminal provided at the other end of the cable 314may be bent toward the lower portion of the main circuit board 700through the cable hole CAH penetrating the bracket 600 and inserted intothe insertion portion of the main connector 730.

The first sound generator 510 may be disposed on the lower surface ofthe panel lower member 400. The first sound generator 510 may beattached to the lower surface of the panel lower member 400 by a firstadhesive member 610 such as a pressure sensitive adhesive. Thus, thedisplay panel 300 may be vibrated by the first sound generator 510 inthe thickness direction (Z-axis direction).

The connection terminal provided at one end of the first flexiblecircuit board 570 may be inserted into the insertion portion of thesecond connector 316. The other end of the first flexible circuit board570 may be connected to the first sound generator 510. The firstflexible circuit board 570 may be a flexible printed circuit (FPC).

The bracket 600 may include a battery hole BH, a cable hole CAH, and afirst camera hole CMH1. The battery hole BH, the cable hole CAH, and thefirst camera hole CMH1 may be holes penetrating the bracket 600.

Because the battery hole BH is a hole for accommodating a battery, thebattery 790 may overlap the battery hole BH along the third direction(Z-axis direction) as shown in FIG. 5. The size of the battery hole BHmay be larger than the size of the battery 790 as shown in FIG. 5.

Because the first camera hole CMH1 of the bracket 600 is a hole foraccommodating the camera device 720 of the main circuit board 700, thecamera device 720 may overlap the first camera hole CMH1 along the thirddirection (Z-axis direction).

According to the embodiment shown in FIGS. 3-5, the first soundgenerator 510 may be electrically connected to the display circuit board310 through the first flexible circuit board 570. The main circuit board700 and the display circuit board 310 may be electrically connected toeach other through the cable 314.

FIG. 5 is a cross-sectional view taken along the line I-I′ of FIG. 3according to an exemplary embodiment.

Referring to FIG. 5, the display panel 300 may include a substrate SUB1,a pixel array layer PAL, and a polarizing film PF.

The substrate SUB1 may be a rigid substrate or a flexible substratecapable of bending, folding, rolling, or the like. The substrate SUB1may be made of an insulating material such as glass, quartz, or apolymer resin. Examples of the polymer resin may includepolyethersulphone (PES), polyacrylate (PA), polyarylate (PAR),polyetherimide (PEI), polyethylenenapthalate (PEN), polyethyleneterepthalate (PET), polyphenylenesulfide (PPS), polyallylate, polyimide(PI), polycarbonate (PC), cellulosetriacetate (CAT), cellulose acetatepropionate (CAP), and combinations thereof. The substrate SUB1 mayinclude a metal material.

The pixel array layer PAL may be disposed on the substrate SUB1. Thepixel array layer PAL may be a layer including pixels PX to display animage. The pixel array layer PAL may include a thin film transistorlayer 303, a light emitting element layer 304, and a thin filmencapsulation layer 305 as shown in FIG. 6.

In order to prevent or reduce the deterioration of visibility due toexternal light reflection, the polarizing film PF may be disposed on thepixel array layer PAL. The polarizing film PF may include a linearpolarizer and a phase retardation film such as a quarter-wave plate. Forexample, the phase retardation film may be disposed on the pixel arraylayer PAL, and the linear polarizer may be disposed between the phaseretardation film and the cover window 100.

The panel lower member 400 may be disposed on the first surface of thedisplay panel 300, and the cover window 100 may be disposed on thesecond surface of the display panel 300, the second surface thereofbeing opposite to the first surface thereof. That is, the panel lowermember 400 may be disposed on the lower surface of the substrate SUB1 ofthe display panel 300, and the cover window 100 may be disposed on theupper surface of the polarizing film PF.

One side of the flexible film 390 may be attached to one side of thesubstrate SUB1, and the other side of the flexible film 390 may beattached to one side of the display circuit board 310. One side of theflexible film 390 may be attached to one surface of the substrate SUB1using an anisotropic conductive film. The other side of the flexiblefilm 390 may be attached to one surface of the display circuit board 310using an anisotropic conductive film. The other surface of the displaycircuit board 310, which is opposite to one surface thereof, may facethe panel lower member 400.

Although it is illustrated in FIG. 5 that the display driving circuit320 is disposed on one surface of the flexible film 390, the presentinvention is not limited thereto. The display drive circuit 320 may bedisposed on the other surface of the flexible film 390, which isopposite to the one surface thereof.

The display circuit board 310 may be disposed on the lower surface ofthe panel lower member 400. The display circuit board 310 may be fixedto the lower surface of the panel lower member 400 by a fixing membersuch as a screw or an adhesive member.

The touch driving circuit 330 and the first sound driver 340 may bedisposed on one surface of the display circuit board 310. The firstconnector 313 and the second connector 316 may be disposed on the othersurface of the display circuit board 310.

The first sound generator 510 may be disposed between the panel lowermember 400 and the bracket 600. The first surface of the first soundgenerator 510 may be attached to the panel lower member 400 by the firstadhesive member 610. Because the first sound generator 510 may be fixedto the panel lower member 400, the display panel 300 may be vibrated bythe vibration of the first sound generator 510. That is, the first soundgenerator 510 may output the first sound by vibrating the display panel300. The first adhesive member 610 may be a pressure sensitive adhesive.The first flexible circuit board 570 may be attached onto the secondsurface of the first sound generator 510.

When the first sound generator 510 is disposed on the heat radiationmember of the panel lower member 400, the first heat radiation layer ofthe heat radiation member may be broken by the vibration of the firstsound generator 510. Therefore, in the area where the first soundgenerator 510 is disposed, the heat radiation member may be removed, andthe first sound generator 510 may be attached to the lower surface ofthe buffer member. Alternatively, in the area where the first soundgenerator 510 is disposed, the buffer member and the heat radiationmember may be removed, and the first sound generator 510 may be attachedto the lower surface of the light absorbing member.

The first flexible circuit board 570 (e.g., a first flexible printedcircuit board) may be attached to the second surface of the first soundgenerator 510 using an anisotropic conductive film. The lead lines ofthe first flexible circuit board 570 may be connected to the first andsecond electrodes of the first sound generator 510, respectively. Theconnection terminal provided at one end of the first flexible circuitboard 570 may be connected to the lead lines. The connection terminal ofthe first flexible circuit board 570 may be inserted into the insertionportion of the second connector 316. The first flexible circuit board570 may be a flexible printed circuit (FPC) or a flexible film.

FIG. 6 is a cross-sectional view specifically showing the display areaof the display panel of FIG. 5 according to an exemplary embodiment.

Referring to FIG. 6, the display panel 300 may include a substrate SUB1and a pixel array layer PAL. The pixel array layer PAL may include athin film transistor layer 303, a light emitting element layer 304, anda thin film encapsulation layer 305 as shown in FIG. 6.

A buffer film 302 may be formed on the substrate SUB1. The buffer film302 may be formed on the substrate SUB1 so as to protect thin filmtransistors 335 and light emitting elements from moisture penetratingthrough the substrate SUB1 which is vulnerable to moisture. The bufferfilm 302 may be formed of a plurality of alternately laminated inorganicfilms. For example, the buffer film 302 may be formed as a multi-layerfilm in which one or more inorganic layers including one or more of asilicon oxide (SiOx), a silicon nitride (SiNx), and SiON are alternatelystacked. In some embodiments, the buffer film 302 may be omitted.

The thin film transistor layer 303 is disposed on the buffer film 302.The thin film transistor layer 303 includes thin film transistors 335, agate insulating film 336, an interlayer insulating film 337, aprotective film 338, and a planarization film 339.

Each of the thin film transistors 335 includes an active layer 331, agate electrode 332, a source electrode 333, and a drain electrode 334.Although it is shown in FIG. 6 that the thin film transistors 335 areformed by a top gate manner in which the gate electrode 332 is locatedon the active layer 331, it should be noted that the present inventionis not limited thereto. That is, the thin film transistors 335 may beformed by a bottom gate manner in which the gate electrode 332 islocated beneath the active layer 331, or may be formed by a double gatemanner in which the gate electrode 332 is located both on and beneaththe active layer 331.

The active layer 331 is formed on the buffer film 302. The active layer331 may be formed of a silicon-based semiconductor material or anoxide-based semiconductor material. A light blocking layer for blockingexternal light incident on the active layer 331 may be formed betweenthe buffer film 302 and the active layer 331.

The gate insulating film 336 may be formed on the active layer 331. Thegate insulating film 336 may be formed of an inorganic film (e.g., asilicon oxide (SiOx) film, a silicon nitride (SiNx) film, or amulti-layer film thereof).

The gate electrode 332 and a gate line may be formed on the gateinsulating film 336. The gate electrode 332 and the gate line may beformed of a single layer or a multi-layer including at least one ofmolybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au), titanium (Ti),nickel (Ni), neodymium (Nd) and copper (Cu), or an alloy thereof.

The interlayer insulating film 337 may be formed on the gate electrode332 and the gate line. The interlayer insulating film 337 may be formedof an inorganic film (e.g., a silicon oxide (SiOx) film, a siliconnitride (SiNx) film, or a multi-layer film thereof).

The source electrode 333, the drain electrode 334, and a data line maybe formed on the interlayer insulating film. Each of the sourceelectrode 333 and the drain electrode 334 may be connected to the activelayer 331 through a contact hole penetrating the gate insulating film336 and the interlayer insulating film 337. The source electrode 333,the drain electrode 334, and the data line may be formed of a singlelayer or a multi-layer including at least one of molybdenum (Mo),aluminum (Al), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni),neodymium (Nd) and copper (Cu), and/or an alloy thereof.

The protective film 338 for insulating the thin film transistor 335 maybe formed on the source electrode 333, the drain electrode 334, and thedata line. The protective film 338 may be formed of an inorganic film(e.g., a silicon oxide (SiOx) film, a silicon nitride (SiNx) film, or amulti-layer film thereof).

The planarization film 339 for flattening a step due to the thin filmtransistor 335 may be formed on the protective film 338. Theplanarization film 339 may be formed of an organic film including anacryl resin, an epoxy resin, a phenolic resin, a polyamide resin, and/ora polyimide resin.

The light emitting element layer 304 is formed on the thin filmtransistor layer 303. The light emitting element layer 304 includeslight emitting elements and a pixel defining film 344.

The light emitting elements and the pixel defining film 344 are formedon the planarization film 339. The light emitting element may be anorganic light emitting element including an anode electrode 341, a lightemitting layer 342, and a cathode electrode 343.

The anode electrode 341 may be formed on the planarization film 339. Theanode electrode 341 may be connected to the source electrode 333 of thethin film transistor 335 through a contact hole penetrating theprotective film 338 and the planarization film 339.

The pixel defining film 344 may be formed on the planarization film 339to cover the edge of the anode electrode 341 so as to define pixels.That is, the pixel defining film 344 serves to define pixels. Each ofthe pixels refers to an area where the anode electrode 341, the lightemitting layer 342, and the cathode electrode 343 are sequentiallylaminated, and holes from the anode electrode 341 and electrons from thecathode electrode 343 are combined with each other in the light emittinglayer 342 to emit light.

The light emitting layers 342 are formed on the anode electrode 341 andthe pixel defining film 344. The light emitting layers 342 are organiclight emitting layers. The light emitting layer 342 may emit one of redlight, green light, and blue light. The light emitting layer 342 may bea white light emitting layer that emits white light. In this case, thelight emitting layer 342 may have a laminate structure of a red lightemitting layer, a green light emitting layer, and a blue light emittinglayer, and may be a common layer formed commonly in the pixels. In thiscase, the display panel 300 may further include separate color filtersfor displaying red, green, and blue colors.

The light emitting layer 342 may include a hole transporting layer, alight emitting layer, and an electron transporting layer. Further, thelight emitting layer 342 may be formed to have a tandem structure of twostacks or more, and in this case, a charge generating layer may beformed between the stacks.

The cathode electrode 343 is formed on the light emitting layer 342. Thecathode electrode 343 may be formed to cover the light emitting layer342. The cathode electrode 343 may be a common layer formed commonly inthe pixels.

When the light emitting element layer 304 is formed according to a topemission manner in which light is emitted upward, the anode electrode341 may be formed of a high-reflectance metal material such as alaminate structure (Ti/Al/Ti) of aluminum and titanium, a laminatestructure (ITO/Al/ITO) of aluminum and TIO, an APC alloy, or a laminatestructure (ITO/APC/ITO) of an APC alloy and ITO. The APC alloy may be analloy of silver (Ag), palladium (Pd), and copper alloy (Cu). The cathodeelectrode 343 may be formed of a transparent conductive material (TCO)such as ITO or IZO, which is light-transmissive, or a semi-transmissiveconductive material such as magnesium (Mg), silver (Ag), or an alloy ofmagnesium (Mg) and silver (Ag). When the cathode electrode 343 is formedof a semi-transmissive conductive material, light emission efficiencymay be increased by microcavities.

When the light emitting element layer 304 is formed by a bottom emissionmanner in which light is emitted downward, the anode electrode 341 maybe formed of a transparent conductive material (TCO) such as ITO or IZO,or a semi-transmissive conductive material such as magnesium (Mg),silver (Ag), or an alloy of magnesium (Mg) and silver (Ag). The cathodeelectrode 343 may be formed of a high-reflectance metal material such asa laminate structure (Ti/Al/Ti) of aluminum and titanium, a laminatestructure (ITO/Al/ITO) of aluminum and TIO, an APC alloy, or a laminatestructure (ITO/APC/ITO) of an APC alloy and ITO. When the anodeelectrode 341 is formed of a semi-transmissive conductive material,light emission efficiency may be increased by microcavities.

The thin film encapsulation layer 305 is formed on the light emittingelement layer 304. The thin film encapsulation layer 305 serves toprevent or reduce oxygen or moisture from permeating the light emittinglayer 342 and the cathode electrode 343. For this purpose, the thin filmencapsulation layer 305 may include at least one inorganic film. Theinorganic film may be formed of silicon nitride, aluminum nitride,zirconium nitride, titanium nitride, hafnium nitride, tantalum nitride,silicon oxide, aluminum oxide, and/or titanium oxide. The thin filmencapsulation layer 305 may further include at least one organic film.The organic film may be formed to have a sufficient thickness tosubstantially prevent or prevent foreign matter (particles) frompenetrating the thin film encapsulation layer 305 and entering the lightemitting layer 342 and the cathode electrode 343. The organic film mayinclude any one of epoxy, acrylate, and urethane acrylate.

A touch sensor layer may be formed on the thin film encapsulation layer305. When the touch sensor layer is formed directly on the thin filmencapsulation layer 305, there is an advantage that the thickness of thedisplay device 10 may be reduced, compared to when a separate touchpanel is attached onto the thin film encapsulation layer 305.

The touch sensor layer may include touch electrodes for sensing a touchof a user in a capacitance manner, and touch lines for connecting thepads and the touch electrodes. For example, the touch sensor layer maysense a user's touch by a self-capacitance manner or a mutualcapacitance manner.

FIG. 7 is a cross-sectional view specifically showing the first soundgenerator of FIG. 5 according to an exemplary embodiment, and FIG. 8 isa view showing a method of vibrating a vibration layer disposed betweenthe first branch electrode and second branch electrode of the firstsound generator of FIG. 7 according to an exemplary embodiment.

Referring to FIGS. 7 and 8, the first sound generator 510 may be apiezoelectric element or a piezoelectric actuator for vibrating thedisplay panel 300 using a piezoelectric material contracting orexpanding depending on the applied voltage. The first sound generator510 may include a vibration layer 511, a first electrode 512, and asecond electrode 513.

The first electrode 512 may include a first stem electrode 5121 andfirst branch electrodes 5122. The first stem electrode 5121 may bedisposed on at least one side surface of the vibration layer 511 asshown in FIG. 7. Alternatively, the first stem electrode 5121 may bedisposed to penetrate a part of the vibration layer 511. The first stemelectrode 5121 may be disposed on the upper surface of the vibrationlayer 511. The first branch electrodes 5122 may be branched from thefirst stem electrode 5121. The first branch electrodes 5122 may bearranged in parallel to each other.

The second electrode 513 may include a second stem electrode 5131 andsecond branch electrodes 5132. The second electrode 513 may be spacedapart from the first electrode 512. Thus, the second electrode 513 maybe electrically separated from the first electrode 512. The second stemelectrode 5131 may be disposed on at least one side surface of thevibration layer 511. In this case, the first stem electrode 5121 may bedisposed on the first side surface of the vibration layer 511, and thesecond stem electrode 5131 may be disposed on the second side surface ofthe vibration layer 511. Alternatively, the second stem electrode 5131may be disposed to penetrate a part of the vibration layer 511. Thesecond stem electrode 5131 may be disposed on the upper surface of thevibration layer 511. The second branch electrodes 5132 may be branchedfrom the second stem electrode 5131. The second branch electrodes 5132may be arranged in parallel to each other.

The first branch electrodes 5122 and the second branch electrodes 5132may be arranged in parallel to each other in the horizontal direction(X-axis direction or Y-axis direction). Further, the first branchelectrodes 5122 and the second branch electrodes 5132 may be alternatelyarranged in the vertical direction (Z-axis direction). That is, thefirst branch electrodes 5122 and the second branch electrodes 5132 maybe arranged repeatedly in the vertical direction (Z-axis direction) inorder of the first branch electrode 5122, the second branch electrode5132, the first branch electrode 5122, and the second branch electrode5132.

The first electrode 512 and the second electrode 513 may be connected tothe pads of the first flexible circuit board 570. The pads of the firstflexible circuit board 570 may be connected to the first electrode 512and second electrode 513 exposed onto one surface of the first soundgenerator 510.

The vibration layer 511 may be a piezoelectric element that is deformedin accordance with a driving voltage applied to the first electrode 512and a driving voltage applied to the second electrode 513. In this case,the vibration layer 511 may be made of any one of a piezoelectricmaterial such as poly vinylidene fluoride (PVDF) or plumbum zirconatetitanate (PZT), and an electroactive polymer.

Because the vibration layer 511 is formed at high temperature, the firstelectrode 512 and the second electrode 513 may be formed of silver (Ag)or an alloy of silver (Ag) and palladium (Pd), each having a highmelting point. When the first electrode 512 and the second electrode 513are formed of an alloy of silver (Ag) and palladium (Pd) to increase themelting points of the first electrode 512 and the second electrode 513,the content of silver (Ag) may be higher than the content of palladium(Pd).

The vibration layer 511 may be disposed between the first branchelectrodes 5122 and the second branch electrodes 5132. The vibrationlayer 511 contracts or expands according to the difference between adriving voltage applied to the first branch electrodes 5122 and adriving voltage applied to the second branch electrodes 5132.

As shown in FIG. 8, the polar direction of the vibration layer 511disposed between the first branch electrode 5122 and the second branchelectrode 5132 disposed under the first branch electrode 5122 may be anupward direction (i), the vibration layer 511 has a positive polarity inthe upper region adjacent to the first branch electrode 5122, and has anegative polarity in the lower region adjacent to the second branchelectrode 5132. Further, the polar direction of the vibration layer 511disposed between the second branch electrode 5132 and the first branchelectrode 5122 disposed under the second branch electrode 5132 may be adownward direction (i), the vibration layer 511 has negative polarity inthe upper region adjacent to the second branch electrode 5132, and haspositive polarity in the lower region adjacent to the first branchelectrode 5122. The polar direction of the vibration layer 511 may bedetermined by a poling process of applying an electric field to thevibration layer 511 using the first branch electrode 5122 and the secondbranch electrode 5132.

As shown in FIG. 8, in the case where the polar direction of thevibration layer 511 disposed between the first branch electrode 5122 andthe second branch electrode 5132 disposed under the first branchelectrode 5122 is the upward direction (i), when a driving voltagehaving positive polarity is applied to the first branch electrode 5122,and a driving voltage having negative polarity is applied to the secondbranch electrode 5132, the vibration layer 511 may be contracted by afirst force F1. The first force F1 may be a contraction force. Further,when a driving voltage having negative polarity is applied to the firstbranch electrode 5122, and a driving voltage having positive polarity isapplied to the second branch electrode 5132, the vibration layer 511 maybe expanded by a second force F2. The second force F2 may be anextension force.

Similarly to FIG. 8, in the case where the polar direction of thevibration layer 511 disposed between the second branch electrode 5132and the first branch electrode 5122 disposed under the second branchelectrode 5132 is the downward direction (↓), when a driving voltagehaving positive polarity is applied to the second branch electrode 5132,and a driving voltage having negative polarity is applied to the firstbranch electrode 5122, the vibration layer 511 may be expanded by theextension force. The first force F1 may be a contraction force. Further,when a driving voltage having negative polarity is applied to the secondbranch electrode 5132, and a driving voltage having positive polarity isapplied to the first branch electrode 5122, the vibration layer 511 maybe contracted by the contraction force.

When the driving voltage applied to the first electrode 512 and thedriving voltage applied to the second electrode 513 are alternatelyrepeated in positive and negative polarities, the vibration layer 511repeats contraction and expansion. Thus, the first sound generator 510vibrates. Because the first sound generator 510 is disposed on onesurface of the heat radiation film 130, the display panel 300 isvibrated in the third direction (Z-axis direction), which is thethickness direction of the display panel 300, by the stress, when thevibration layer 511 of the first sound generator 510 contracts andexpands. Therefore, the display panel 300 may be vibrated by the firstsound generator 510, thereby outputting the first sound.

A protective layer 519 may be additionally provided on the secondsurface and side surfaces of the first sound generator 510. Theprotective layer 519 may be formed of an insulating material, or may beformed of the same material as the vibration layer 511. The protectivelayer 519 may be disposed on the first electrode 512, the secondelectrode 513, and the vibration layer 511 exposed by the firstelectrode 512 and the second electrode 513 without being covered by thefirst electrode 512 and the second electrode 513. The protective layer519 may be disposed to surround the first electrode 512, the secondelectrode 513, and the vibration layer 511 exposed by the firstelectrode 512 and the second electrode 513 without being covered by thefirst electrode 512 and the second electrode 513. Therefore, thevibration layer 511, the first electrode 512 and the second electrode513 of the first sound generator 510 may be protected by the protectionlayer 519. In some embodiments, the protective layer 519 may be omitted.

FIG. 9 is a perspective view specifically showing the second soundgenerator of FIG. 5 according to an exemplary embodiment.

Referring to FIG. 9, the second sound generator 520 may be a linearresonance actuator (LRA) that vibrates the display panel 300 bygenerating a magnetic force using a voice coil. The second soundgenerator 520 may include a lower chassis 521, a flexible circuit board522, a voice coil 523, a magnet 524, a spring 525, and an upper chassis526.

The lower chassis 521 and the upper chassis 526 may be formed of a metalmaterial. The flexible circuit board 522 may be disposed on one surfaceof the lower chassis 521 facing the upper chassis 526, and may beconnected to a second flexible circuit board 527. The voice coil 523 maybe connected to one surface of the flexible circuit board 522 facing theupper chassis 526. Thus, one end of the voice coil 523 may beelectrically connected to one of the lead lines of the second flexiblecircuit board 527, and the other end of the voice coil 523 may beelectrically connected to the other one of the lead lines of the secondflexible circuit board 527. The magnet 524 is a permanent magnet, andone surface of the magnet 524, facing the voice coil 523, may beprovided with a voice coil groove 524 a for accommodating the voice coil523. The spring 525, which is an elastic body, is disposed between themagnet 524 and the upper chassis 526.

The direction of a current flowing in the voice coil 523 may becontrolled by the first driving voltage applied to one end of the voicecoil 523 and the second driving voltage applied to the other end of thevoice coil 523. An applied magnetic field may be formed around the voicecoil 523 in accordance with the current flowing in the voice coil 523.That is, the direction of the current flowing in the voice coil 523 whenthe first driving voltage is a positive polarity voltage and the seconddriving voltage is a negative polarity voltage is opposite to thedirection of the current flowing in the voice coil 523 when the firstdriving voltage is a negative polarity and the second driving voltage isa positive polarity voltage. An attracting force and a repulsive forcealternately act on the magnet 524 and the voice coil 523 in accordancewith the AC driving of the first driving voltage and the second drivingvoltage. Therefore, the magnet 524 may reciprocate between the voicecoil 523 and the upper chassis 526 by the spring 525.

Meanwhile, the vibration due to the reciprocation of the magnet 524 maybe transmitted to both the lower chassis 521 and the upper chassis 526.Therefore, the lower chassis 521 may face the bracket 600, and the upperchassis 526 may face the display panel 300. Alternatively, the lowerchassis 521 may face the display panel 300, and the upper chassis 526may face the bracket 600.

According to the embodiment shown in FIG. 9, the bracket 600 may bevibrated by the reciprocation of the magnet 524 of the second soundgenerator 520, thereby outputting the second sound or providing a hapticsense.

FIG. 10 is a flowchart showing a sound providing method of a displaydevice according to an exemplary embodiment.

Referring to FIG. 10, first, the main processor 710 may select one of afirst sound mode and a second sound mode (S101 of FIG. 10).

The first sound mode may be a mode for preventing or reducing thedeterioration of sound quality due to harmonic tones of the first sound,and the second sound mode may be a mode for providing a sound havingboth a low frequency band and a high frequency band to a user.

Second, the main processor 710 may generate first sound data in thefirst sound mode and output the first sound data to the phase shifter750 (S102 of FIG. 10).

The main processor 710 receives sound source data from the outside. Themain processor 710 outputs the sound source data to the memory 740 andreceives sound data from the memory 740. Because the memory 740 storesthe sound data according to the frequency of the sound source data, thememory 740 may output the sound data to the main processor 710 using thefrequency of the sound source data as an input address. The mainprocessor 710 may generate the first sound data according to the sounddata input from the memory 740. The main processor 710 outputs the firstsound data to the phase shifter 750.

Third, the phase shifter 750 shifts the phase of each of a fundamentaltone FT1 and first to fourth harmonic tones HT11, HT12, HT13, and HT14of the first sound as shown in FIG. 11 to generate a fundamental toneFT2 and first to fourth harmonic tones HT21, HT22, HT23, and HT24 of thesecond sound as shown in FIG. 12. The phase shifter 750 may shift thephase of the fundamental tone FT1 of the first sound to generate thefundamental tone FT2 of the second sound so as to obtain the effect that(i.e., such that) the fundamental tone FT1 of the first sound isamplified (e.g., due to constructive interference) by the fundamentaltone FT2 of the second sound. Further, the phase shifter 750 may shiftthe phase of each of the first to fourth harmonic tones HT11, HT12,HT13, and HT14 of the first sound to generate the first to fourthharmonic tones HT21, HT22, HT23, and HT24 of the second sound so as toobtain the effect that (i.e., such that) the first to fourth harmonictones HT11, HT12, HT13, and HT14 of the first sound are offset (e.g.,due to destructive interference) by the first to fourth harmonic tonesHT21, HT22, HT23, and HT24 of the second sound (S103 of FIG. 10).

The phase shifter 750 modulates first sound data and outputs secondsound data. The first sound includes a fundamental tone FT1 and harmonictones HT11, HT12, HT13, and HT14, and the second sound includes afundamental tone FT2 and harmonic tones HT21, HT22, HT23, and HT24. Thefirst sound data includes information about the frequency and the soundpressure level or amplitude of a fundamental tone of the first sound,and the first sound data includes information about the frequencies andthe sound pressure levels or amplitudes of harmonic tones of the firstsound. The second sound data includes information about the frequencyand the sound pressure level or amplitude of a fundamental tone of thesecond sound, and the second sound data includes information about thefrequencies and the sound pressure levels or amplitudes of harmonictones of the second sound.

The phase shifter 750 shifts the phase of the fundamental tone FT1 ofthe first sound (shown in FIG. 11) to generate the fundamental tone FT2of the second sound (shown in FIG. 12), in order for the sound pressurelevel of a fundamental tone FT3 of the third sound (shown in FIG. 13),which is a sum of the first sound and the second sound, to be higherthan (or greater than) the sound pressure level of the fundamental toneFT1 of the first sound. The time period during which the positiveamplitude region of the fundamental tone FT1 of the first sound overlapsthe positive amplitude region of the fundamental tone FT2 of the secondsound may be T/2 or more as shown in FIG. 14. Therefore, the differencebetween the phase θ1 of the fundamental tone FT1 of the first sound andthe phase θ2 of the fundamental tone FT2 of the second sound may be in arange from −90° to 90° as shown in FIG. 15. In this case, the amplitudeC of the fundamental tone FT3 of the third sound may be larger than (orgreater than) the amplitude A of the fundamental tone FT1 of the firstsound and the amplitude B of the fundamental tone FT2 of the secondsound.

It is illustrated in FIG. 14 that each of the period of the fundamentaltone FT1 of the first sound and the period of the fundamental tone FT2of the second sound is 2 T. Further, it is illustrated in FIG. 14 thateach of the amplitude of the fundamental tone FT1 of the first sound andthe amplitude of the fundamental tone FT2 of the second sound is H.Further, it is illustrated in FIG. 15 that the amplitude of thefundamental tone FT1 of the first sound is A and the phase thereof isθ1, the amplitude of the fundamental tone FT2 of the second sound is Band the phase thereof is θ2, and the amplitude of the fundamental toneFT3 of the third sound is C and the phase thereof is θ3. In FIG. 15, 01may be 0°, each of θ2 and θ3 may be less than 90°, and θ3 may have avalue between θ1 and θ2.

The phase shifter 750 shifts the phases of the respective harmonic tonesHT11, HT12, HT13 and HT14 of the first sound to generate the harmonictones HT21, HT22, HT23 and HT24 of the second sound. In order for thesound pressure level of each of the harmonic tones HT31, HT32, HT33, andHT34 of the third sound to be lower than (or less than) the soundpressure level of each of the harmonic tones HT11, HT12, HT13, and HT14of the first sound, the difference between the phase of each of theharmonic tones HT11, HT12, HT13 and HT14 of the first sound and thephase of each of the harmonic tones HT21, HT22, HT23, and HT24 of thesecond sound may be within the second range.

For example, in order for the sound pressure level of the first harmonictone HT31 of the third sound (shown in FIG. 13) to be lower than (orless than) the sound pressure level of the first harmonic tone HT11 ofthe first sound (shown in FIG. 11), the time period during which thepositive amplitude region of the first harmonic tone HT11 of the firstsound overlaps the negative amplitude region of the first harmonic toneHT21 of the second sound may be T/4 or more as shown in FIG. 16.Therefore, the difference between the phase θ4 of the first harmonictone HT11 of the first sound and the phase θ5 of the first harmonic toneHT21 of the second sound may be less than −90° and more than 90° asshown in FIG. 17. In this case, the amplitude F of the first harmonictone HT31 of the third sound may be smaller than (or less than) theamplitude D of the first harmonic tone HT11 of the first sound and theamplitude E of the first harmonic tone HT21 of the second sound.

In FIG. 16, each of the period of the fundamental tone FT1 of the firstsound and the period of the fundamental tone FT2 of the second sound is1 T. Further, as shown in FIG. 16, each of the amplitude of the firstharmonic tone HT11 of the first sound and the amplitude of the firstharmonic tone HT21 of the second sound is G. Further, as shown in FIG.17, the amplitude of the first harmonic tone HT11 of the first sound isD and the phase thereof is θ4, the amplitude of the first harmonic toneHT21 of the second sound is E and the phase thereof is θ5, and theamplitude of the first harmonic tone HT31 of the first sound is F andthe phase thereof is θ6. In FIG. 17, θ4 may be 0°, 05 may be more than90°, and θ6 may have a value between θ4 and θ5.

As shown in FIG. 13, in order for the sound pressure level of the secondharmonic tone HT32 of the third sound to be lower than (or less than)the sound pressure level of the second harmonic tone HT12 of the firstsound, the time period during which the positive amplitude region of thesecond harmonic tone HT12 of the first sound overlaps the negativeamplitude region of the second harmonic tone HT22 of the second soundmay be T/4 or more. In this case, the difference between the phase ofthe second harmonic tone HT12 of the first sound and the phase of thesecond harmonic tone HT22 of the second sound may be less than −90° andmore than 90°. Further, the amplitude of the second harmonic tone HT32of the third sound may be smaller than (or less than) the amplitude ofthe second harmonic tone HT12 of the first sound and the amplitude ofthe second harmonic tone HT22 of the second sound.

As shown in FIG. 13, in order for the sound pressure level of the thirdharmonic tone HT33 of the third sound to be lower than (or less than)the sound pressure level of the third harmonic tone HT13 of the firstsound, the time period during which the positive amplitude region of thethird harmonic tone HT13 of the first sound overlaps the negativeamplitude region of the third harmonic tone HT23 of the second sound maybe T/4 or more. Therefore, the difference between the phase of the thirdharmonic tone HT13 of the first sound and the phase of the thirdharmonic tone HT23 of the second sound may be less than −90° and morethan 90°. Further, the amplitude of the third harmonic tone HT33 of thethird sound may be smaller than (or less than) the amplitude of thethird harmonic tone HT13 of the first sound and the amplitude of thethird harmonic tone HT23 of the second sound.

As shown in FIG. 13, in order for the sound pressure level of the fourthharmonic tone HT34 of the third sound to be lower than (or less than)the sound pressure level of the fourth harmonic tone HT14 of the firstsound, the time period during which the positive amplitude region of thefourth harmonic tone HT14 of the first sound overlaps the negativeamplitude region of the fourth harmonic tone HT24 of the second soundmay be T/4 or more. For this, the difference between the phase of thefourth harmonic tone HT14 of the first sound and the phase of the fourthharmonic tone HT24 of the second sound may be less than −90° and morethan 90°. Further, the amplitude of the fourth harmonic tone HT34 of thethird sound may be smaller than (or less than) the amplitude of thefourth harmonic tone HT14 of the first sound and the amplitude of thefourth harmonic tone HT24 of the second sound.

Because the phase shifter 750 shifts the phase of each of thefundamental tone and harmonic tones of the first sound to generate thefundamental tone and harmonic tones of the second sound, the frequencyof the fundamental tone FT1 of the first sound may be substantially thesame as the frequency of the fundamental tone FT2 of the second sound.Further, the frequency of each of the harmonic tones HT11, HT12, HT13and HT14 of the first sound may be substantially the same as thefrequency of each of the harmonic tones HT21, HT22, HT23 and HT24 of thesecond sound. For example, the frequency of the first harmonic tone HT11of the first sound may be substantially the same as the frequency of thefirst harmonic tone HT21 of the second sound. The frequency of thesecond harmonic tone HT12 of the first sound may be substantially thesame as the frequency of the second harmonic tone HT22 of the secondsound. The frequency of the third harmonic tone HT13 of the first soundmay be substantially the same as the frequency of the third harmonictone HT23 of the second sound. The frequency of the fourth harmonic toneHT14 of the first sound may be substantially the same as the frequencyof the fourth harmonic tone HT24 of the second sound.

The sound pressure level or amplitude of the fundamental tone FT1 of thefirst sound may be different from the sound pressure level or amplitudeof the fundamental tone FT2 of the second sound. When the sound pressurelevel or amplitude of the first harmonic tone HT11 of the first sound issubstantially the same as the sound pressure level or amplitude of thefirst harmonic tone HT21 of the second sound, the sound pressure levelof the first harmonic tone HT31 of the third sound may be reduced orminimized. However, even when the sound pressure level or amplitude ofthe first harmonic tone HT11 of the first sound is different from thesound pressure level or amplitude of the first harmonic tone HT21 of thesecond sound, the sound pressure level or amplitude of the firstharmonic tone HT31 of the third sound may be lower than (or less than)the sound pressure level or amplitude of the first tone HT11 of thefirst sound. Accordingly, the sound pressure level or amplitude of thefirst harmonic tone HT11 of the first sound may not be substantially thesame as the sound pressure level or amplitude of the first harmonic toneHT21 of the second sound. The sound pressure level or amplitude of thesecond harmonic tone HT12 of the first sound may also be substantiallythe same as or different from the sound pressure level or amplitude ofthe second harmonic tone HT22 of the second sound. The sound pressurelevel or amplitude of the third harmonic tone HT13 of the first soundmay also be substantially the same as or different from the soundpressure level or amplitude of the third harmonic tone HT23 of thesecond sound. The sound pressure level or amplitude of the fourthharmonic tone HT14 of the first sound may also be substantially the sameas or different from the sound pressure level or amplitude of the fourthharmonic tone HT24 of the second sound.

Meanwhile, in order to obtain an amplification effect that the soundpressure level of the fundamental tone of the third sound, which is asum of the first sound and the second sound, becomes higher than (orgreater than) the sound pressure level of the fundamental tone of thefirst sound or to obtain an offset effect that the sound pressure levelof at least one of the harmonic tones of the third sound becomes lowerthan (or less than) the sound pressure level of at least one of theharmonic tones of the first sound, information about the distancebetween the first sound generator 510 and the second sound generator 520is desirable. The phase shifter 750 stores the information about thedistance between the first sound generator 510 and the second soundgenerator 520. Therefore, in order to obtain the desired amplificationeffect or the desired offset effect, the phase shifter 750 may calculatehow much the phase of each of the fundamental tone and harmonic tones ofthe first sound should be shifted.

The phase shifter 750 may output second sound data including informationabout the frequency and sound pressure level or amplitude of afundamental tone of the second sound to the second sound driver 760, andmay output second sound data including information about the frequenciesand sound pressure levels or amplitudes of harmonic tones of the secondsound in the first sound mode to the second sound driver 760.

Meanwhile, for convenience of explanation, it is shown in FIGS. 11-13that the harmonic tones of the second sound, having opposite phases tothe harmonic tones of the first sound, are arranged in a directionopposite to the Y-axis direction (i.e., harmonic tones having opposingphases are arranged on opposing sides of the Y-axis).

In the act S103 of FIG. 10, due to the phase shifter 750, anamplification effect that the sound pressure level of the fundamentaltone of the third sound, which is a sum of the first sound and thesecond sound, becomes higher than (or greater than) the sound pressurelevel of the fundamental tone of the first sound can be obtained, andconcurrently (e.g., simultaneously) an offset effect that the soundpressure level of any one of the harmonic tones of the third soundbecomes lower than (or less than) the sound pressure level of any one ofthe harmonic tones of the first sound can be obtained. Therefore, it ispossible to prevent or reduce the deterioration of sound qualityprovided to the user due to the harmonic tones of the first sound and toprovide a high-quality sound by increasing the sound pressure level ofthe fundamental tone of the first sound.

Fourth, the main processor 710 may generate first sound data and secondsound data in the second sound mode and output the first sound data andthe second sound data to the phase shifter 750 (S104 of FIG. 10).

The main processor 710 outputs sound source data to the memory 740 andreceives sound data from the memory 740. Because the memory 740 storesthe sound data according to the frequency of the sound source data, thememory 740 may output the sound data to the main processor 710 using thefrequency of the sound source data as an input address. The mainprocessor 710 may generate the first sound data and the second sounddata according to the sound data input from the memory 740. The mainprocessor 710 outputs the first sound data and the second sound data tothe phase shifter 750.

Fifth, the phase shifter 750 shifts the phase of the harmonic tone ofthe second sound having the same frequency as any one of the fundamentaltone and harmonic tones of the first sound (S105 of FIG. 10).

When the first sound generator 510 is a piezoelectric element or apiezoelectric actuator and the second sound generator 520 is a linearresonant actuator LRA, the first sound generator 510 outputs a firstsound of a relatively higher frequency band than the second soundgenerator 520, and the second sound generator 520 outputs a second soundof a relatively lower frequency band than the first sound generator 510.For example, as shown in FIG. 18, when the first frequency band F1indicating the frequency band of the first sound is 0 Hz to 800 Hz(e.g., the frequency band could be 100 Hz to 800 Hz in otherembodiments) and the second frequency band F2 indicating the frequencyband of the second sound is 600 Hz to 2 kHz, the third frequency band F3in which the first frequency band F1 and the second frequency band F2overlap each other may be 600 Hz to 800 Hz. The phase shifter 750 mayincrease the sound pressure level of the fundamental tone of the firstsound or decrease the sound pressure level of any one of the harmonictones of the first sound by using the harmonic tones of the second soundhaving the same frequency as each of the fundamental tone and harmonictones of the third frequency band F3 from among the fundamental tone andharmonic tones of the first sound.

The phase shifter 750 may shift the phase of any one harmonic tone ofthe second sound having the same frequency as the fundamental tone ofthe first sound. In order to increase the sound pressure level of thefundamental tone of the first sound, the time period during which thepositive amplitude region of the fundamental tone of the first soundoverlaps the positive amplitude region of any one harmonic tone of thesecond sound may be T/4 or more. In this case, the difference betweenthe phase of the fundamental tone of the first sound and the phase ofany one harmonic tone of the second sound may be in a range from −90° to90°.

The phase shifter 750 may shift the phase of another harmonic tone ofthe second sound having the same frequency as any one harmonic tone ofthe first sound. In order to increase the sound pressure level of anyone harmonic tone of the first sound, the time period during which thepositive amplitude region of any one harmonic tone of the first soundoverlaps the negative amplitude region of another harmonic tone of thesecond sound may be T/4 or more. In this case, the difference betweenthe phase of any one harmonic tone of the first sound and the phase ofanother harmonic tone of the second sound may be less than −90° and morethan 90°.

The phase shifter 750 may output the first sound data to the first sounddriver 340 in the second sound mode, and may output the second sounddata to the second sound driver 760 in the second sound mode.

In the act S105 of FIG. 10, due to the phase shifter 750, anamplification effect of increasing the sound pressure level of thefundamental tone of the first sound can be obtained, and concurrently(e.g., simultaneously) an offset effect of decreasing the sound pressurelevel of any one of the harmonic tones of the first sound can beobtained. Therefore, it is possible to prevent or reduce thedeterioration of sound quality provided to the user due to the harmonictones of the first sound and to provide a high-quality sound byincreasing the sound pressure level of the fundamental tone of the firstsound.

Sixth, the first sound driver 340 may generate first sound signalsaccording to the first sound data and output the first sound signals tothe first sound generator 510, and may generate second sound signalsaccording to the second sound data and output the second sound signalsto the second sound generator 520 (S106 of FIG. 10).

The first sound driver 340 receives the first sound data from the maincircuit board 700. The first sound driver 340 may generate the firstsound signals including first and second sound driving voltagesaccording to the first sound data. For this purpose, the first sounddriver 340 may include a digital signal processor (DSP) for processingsound data which are digital signals, a digital-analog converter (DAC)for converting the sound data output from the digital signal processorinto sound driving voltages which are analog signals, and an amplifier(AMP) for amplifying and outputting the sound driving voltages. Thefirst sound driver 340 may output the first sound signals to the firstsound generator 510.

The second sound driver 760 receives the second sound data from thephase shifter 750. The second sound driver 760 may generate the secondsound signals including third and fourth sound driving voltagesaccording to the second sound data. For this purpose, the second sounddriver 760 may include a digital signal processor (DSP) for processingsound data which are digital signals, a digital-analog converter (DAC)for converting the sound data output from the digital signal processorinto sound driving voltages which are analog signals, and an amplifier(AMP) for amplifying and outputting the sound driving voltages. Thesecond sound driver 760 may output the second sound signals to thesecond sound generator 520.

The first sound generator 510 may vibrate the display panel 300according to the first sound signals, and thus the first sound may beoutput. The second sound generator 520 may vibrate the display panel 300according to the second sound signals, and thus the second sound may beoutput.

FIG. 19 is a flowchart showing a sound providing method of a displaydevice according to an exemplary embodiment.

The acts S201, S202, S204, and S206 in the embodiment shown in FIG. 19are substantially the same as the acts S101, S102, S104, and S106 in theembodiment shown in FIG. 10, except for the step S203 and S205.Therefore, a description of the acts S201, S202, S204, and S206 in theembodiment shown in FIG. 19 may be omitted (e.g., may not be repeated).

Referring to FIG. 19, the phase shifter 750 shifts the phase of each ofthe fundamental tone FT1 and first to fourth harmonic tones HT11, HT12,HT13, and HT14 of the first sound as shown in FIG. 20 to generate afundamental tone FT2 and first to fourth harmonic tones HT21, HT22,HT23, and HT24 of the second sound as shown in FIG. 21. The phaseshifter 750 may shift the phase of the fundamental tone FT1 of the firstsound so as to obtain the effect that the fundamental tone FT1 of thefirst sound is amplified by the fundamental tone FT2 of the second soundto generate the fundamental tone FT2 of the second sound. Further, thephase shifter 750 may shift the phase of each of the first harmonic toneHT11 and third harmonic tone HT13 of the first sound to generate thefirst harmonic tone HT21 and the third harmonic tone HT23 of the secondsound so as to obtain the effect that the first harmonic tone HT11 andthe third harmonic tone HT13 each having a frequency even numbered timesof that of the fundamental tone FT1 of the first sound are amplified bythe first harmonic tone HT21 and third harmonic tone HT23 of the secondsound. Further, the phase shifter 750 may shift the phase of each of thesecond harmonic tone HT12 and fourth harmonic tone HT14 of the firstsound to generate the second harmonic tone HT22 and the fourth harmonictone HT24 of the second sound so as to obtain the effect that the secondharmonic tone HT12 and fourth harmonic tone HT14 each having a frequencyodd numbered times of that of the fundamental tone FT1 of the firstsound are offset by the second harmonic tone HT22 and the fourthharmonic tone HT24 of the second sound (S203 of FIG. 19).

For example, when the frequency of the fundamental tone FT1 of the firstsound is 300 Hz, the frequency of the first harmonic tone HT11 of thefirst sound having a frequency two times of that of the fundamental toneFT1 of the first sound may be 600 Hz, and the frequency of the secondharmonic tone HT12 of the first sound having a frequency three times ofthat of the fundamental sound FT1 of the first sound may be 900 Hz.Further, the frequency of the third harmonic tone HT13 of the firstsound having a frequency four times of that of the fundamental tone FT1of the first sound may be 1200 Hz, and the frequency of the fourthharmonic tone HT14 of the first sound having a frequency five times ofthat of the fundamental sound FT1 of the first sound may be 1500 Hz.

The phase shifter 750 modulates first sound data and outputs secondsound data. The first sound includes a fundamental tone FT1 and harmonictones HT11, HT12, HT13, and HT14, and the second sound includes afundamental tone FT2 and harmonic tones HT21, HT22, HT23, and HT24. Thefirst sound data includes information about the frequency and the soundpressure level or amplitude of a fundamental tone of the first sound,and information about the frequencies and the sound pressure levels oramplitudes of harmonic tones of the first sound. The second sound dataincludes information about the frequency and the sound pressure level oramplitude of a fundamental tone of the second sound, and informationabout the frequencies and the sound pressure levels or amplitudes ofharmonic tones of the second sound.

Because a description that the phase shifter 750 shifts the phase of thefundamental tone FT1 of the first sound to generate the fundamental toneFT2 of the second sound, and shifts the phase of each of the secondharmonic tone HT12 and fourth harmonic tone HT24 of the second sound togenerate the second harmonic tone HT22 and fourth harmonic tone HT24 ofthe second sound is substantially the same as that having been describedin the act S103 of FIG. 10, the description thereof may be omitted(e.g., may not be repeated).

In order for the sound pressure level of the first harmonic tone HT31 ofthe third sound to be higher than (or greater than) the sound pressurelevel of the first harmonic tone HT11 of the first sound, the timeperiod during which the positive amplitude region of the first harmonictone HT11 of the first sound overlaps the positive amplitude region ofthe first harmonic tone HT21 of the second sound may be ¼ or more of theperiod of the first harmonic tone HT11 of the first sound. For this, thedifference between the phase of the first harmonic tone HT11 of thefirst sound and the phase of the first harmonic tone HT21 of the secondsound may be in a range from −90° to 90°. In this case, the amplitude ofthe first harmonic tone HT31 of the third sound may be larger than (orgreater than) the amplitude of the first harmonic tone HT11 of the firstsound and the amplitude of the first harmonic tone HT21 of the secondsound.

In order for the sound pressure level of the third harmonic tone HT33 ofthe third sound to be higher than (or greater than) the sound pressurelevel of the third harmonic tone HT13 of the first sound, the timeperiod during which the positive amplitude region of the third harmonictone HT13 of the first sound overlaps the positive amplitude region ofthe third harmonic tone HT23 of the second sound may be ¼ or more of theperiod of the third harmonic tone HT13 of the first sound. For this, thedifference between the phase of the third harmonic tone HT13 of thefirst sound and the phase of the third harmonic tone HT23 of the secondsound may be in a range from −90° to 90°. In this case, the amplitude ofthe third harmonic tone HT33 of the third sound may be smaller than (orless than) the amplitude of the third harmonic tone HT13 of the firstsound and the amplitude of the third harmonic tone HT23 of the secondsound.

Because the phase shifter 750 shifts each of the fundamental tone andharmonic tones of the first sound to generate the fundamental tone andharmonic tones of the second sound, the frequency of the fundamentaltone FT1 of the first sound may be substantially the same as thefrequency of the fundamental tone FT2 of the second sound. Further, thefrequency of each of the harmonic tones HT11, HT12, HT13, and HT14 ofthe first sound may be substantially the same as the frequency of eachof the harmonic tones HT21, HT22, HT23, and HT24 of the second sound.For example, the frequency of the first harmonic tone FT11 of the firstsound may be substantially the same as the frequency of the firstharmonic tone FT21 of the second sound. The frequency of the secondharmonic tone FT12 of the first sound may be substantially the same asthe frequency of the second harmonic tone FT22 of the second sound. Thefrequency of the third harmonic tone FT13 of the first sound may besubstantially the same as the frequency of the third harmonic tone FT23of the second sound.

The frequency of the fourth harmonic tone FT14 of the first sound may besubstantially the same as the frequency of the fourth harmonic tone FT24of the second sound.

The sound pressure level or amplitude of the fundamental tone FT1 of thefirst sound may be different from the sound pressure level or amplitudeof the fundamental tone FT2 of the second sound. The sound pressurelevel or amplitude of the first harmonic tone HT11 of the first soundmay be different from the sound pressure level or amplitude of the firstharmonic tone HT21 of the second sound. The sound pressure level oramplitude of the third harmonic tone HT13 of the first sound may bedifferent from the sound pressure level or amplitude of the thirdharmonic tone HT23 of the second sound.

When the sound pressure level or amplitude of the second harmonic toneHT12 of the first sound is substantially the same as the sound pressurelevel or amplitude of the second harmonic tone HT22 of the second sound,the sound pressure level of the second harmonic tone HT32 of the thirdsound may be minimized or reduced. However, even when the sound pressurelevel or amplitude of the second harmonic tone HT12 of the first soundis different from the sound pressure level or amplitude of the secondharmonic tone HT22 of the second sound, the sound pressure level oramplitude of the second harmonic tone HT32 of the third sound may belower than (or less than) the sound pressure level or amplitude of thesecond tone HT12 of the first sound. Accordingly, in some embodiments,the sound pressure level or amplitude of the second harmonic tone HT12of the first sound may not be substantially the same as the soundpressure level or amplitude of the second harmonic tone HT22 of thesecond sound. The sound pressure level or amplitude of the fourthharmonic tone HT14 of the first sound may also be substantially the sameas or different from the sound pressure level or amplitude of the fourthharmonic tone HT24 of the second sound.

Meanwhile, in order to obtain an amplification effect that the soundpressure level of the fundamental tone of the third sound, which is asum of the first sound and the second sound, becomes higher than (orgreater than) the sound pressure level of the fundamental tone of thefirst sound or to obtain an offset effect that the sound pressure levelof at least one of the harmonic tones of the third sound becomes lowerthan (or less than) the sound pressure level of at least one of theharmonic tones of the first sound, information about the distancebetween the first sound generator 510 and the second sound generator 520is desirable. The phase shifter 750 stores the information about thedistance between the first sound generator 510 and the second soundgenerator 520. Therefore, in order to obtain the amplification effect orthe offset effect, the phase shifter 750 may calculate how much thephase of each of the fundamental tone and harmonic tones of the firstsound should be shifted.

According to the act S203 of FIG. 19, due to the phase shifter 750, anoffset effect that the sound pressure levels of the harmonic tones eachhaving a different tone from the fundamental tone of the first sound canbe obtained, and concurrently (e.g., simultaneously) an amplificationeffect that the sound pressure levels of the harmonic tones each havingthe same tone as the fundamental tone of the first sound can beobtained. Therefore, it is possible to prevent or reduce thedeterioration of sound quality provided to the user due to the harmonictones each having a different tone from the fundamental tone of thefirst sound and to provide a high-quality sound by increasing the soundpressure levels of the harmonic tones each having the same tone as thefundamental tone of the first sound.

Further, the phase shifter 750 shifts the phase of the harmonic tone ofthe second sound, having the same frequency as the fundamental tone orat least one harmonic tone of the first sound. The phase shifter 750 mayshift the phase of the harmonic tone of the second sound, having thesame frequency as the fundamental tone FT1 of the first sound, so as toobtain the effect that the fundamental tone FT1 of the first sound isamplified by the harmonic tone of the second sound. Further, the phaseshifter 750 may shift the phase of the harmonic tone of the secondsound, having a frequency even numbered times of that of the fundamentaltone of the first sound, so as to obtain the effect that the harmonictone of the first sound, having a frequency even numbered times of thatof the fundamental tone of the first sound, is amplified by the harmonictone of the second sound. Further, the phase shifter 750 may shift thephase of the harmonic tone of the second sound, having a frequency oddnumbered times of that of the fundamental tone of the first sound, so asto obtain the effect that the harmonic tone of the first sound, having afrequency odd numbered times of that of the fundamental tone of thefirst sound, is offset by the harmonic tone of the second sound (S205 ofFIG. 19).

The phase shifter 750 may shift the phase of the harmonic tone of thesecond sound, having the same frequency as the fundamental tone of thefirst sound. In order to increase the sound pressure level of thefundamental tone of the first sound, the time period during which thepositive amplitude region of the fundamental tone of the first soundoverlaps the positive amplitude region of the harmonic tone of thesecond sound may be ¼ or more of the period of the fundamental tone ofthe first sound. In this case, the difference between the phase of thefundamental tone of the first sound and the phase of the harmonic toneof the second sound may be in a range from −90° to 90°.

The phase shifter 750 may shift the phase of the harmonic tone of thesecond sound, having the same frequency as the harmonic tone having afrequency odd numbered times of that of the fundamental tone of thefirst sound. In order to increase the sound pressure level of theharmonic tone having a frequency odd numbered times of that of thefundamental tone of the first sound, the time period during which thepositive amplitude region of the harmonic tone having a frequency oddnumbered times of that of the fundamental tone of the first soundoverlaps the negative amplitude region of the harmonic tone of thesecond sound may be ¼ or more of the harmonic tone having a frequencyodd numbered times of that of the fundamental tone of the first sound.In this case, the difference between the phase of the harmonic tonehaving a frequency odd numbered times of that of the fundamental tone ofthe first sound and the phase of the harmonic tone of the second soundmay be less than −90° and more than 90°.

The phase shifter 750 may output the first sound data to the first sounddriver 340 in the second sound mode, and may output the second sounddata to the second sound driver 760 in the second sound mode.

According to the act S205 of FIG. 19, due to the phase shifter 750, anoffset effect that the sound pressure levels of the harmonic tones eachhaving a different tone from the fundamental tone of the first sound canbe obtained, and concurrently (e.g., simultaneously) an amplificationeffect that the sound pressure levels of the harmonic tones each havingthe same tone as the fundamental tone of the first sound can beobtained. Therefore, it is possible to prevent or reduce thedeterioration of sound quality provided to the user due to the harmonictones each having a different tone (i.e., the harmonic tones having afrequency that is an odd integer multiple of the frequency of thefundamental tone) from the fundamental tone of the first sound and toprovide a high-quality sound by increasing the sound pressure levels ofthe harmonic tones each having the same tone (i.e., the harmonic toneshaving a frequency that is an even integer multiple of the frequency ofthe fundamental tone) as the fundamental tone of the first sound.

FIG. 23 is a bottom view showing a bracket attached to the lower surfaceof the display panel of FIG. 3 and a main circuit board disposed on thebracket according to an exemplary embodiment.

The embodiment shown in FIG. 23 is different from the embodiment shownin FIG. 4 in that the memory 740, instead of the phase shifter 750,includes a look-up table 741. In FIG. 23, a description substantiallythe same as the embodiment shown in FIG. 4 may be omitted (e.g., may notbe repeated).

Referring to FIG. 23, the look-up table 741 receives frequencyinformation of a fundamental tone and harmonic tones of a first soundfrom the main processor 710 in the first sound mode. The look-up table741 stores information about a fundamental tone and harmonic tones of asecond sound according to the frequency of each of the fundamental toneand harmonic tones of the first sound. The look-up table 741 may outputthe information about the fundamental tone and harmonic tones of thesecond sound using the frequency of each of the fundamental tone andharmonic tones of the first sound as an input address. The mainprocessor 710 may generate second sound data in the first sound modeusing the information about the fundamental tone and harmonic tones ofthe second sound input from the look-up table 741, and may output thesecond sound data to the second sound driver 760.

According to the embodiment shown in FIG. 23, due to the look-up table741, an amplification effect that the sound pressure level of thefundamental tone of the third sound, which is a sum of the first soundand the second sound, becomes higher than (or greater than) the soundpressure level of the fundamental tone of the first sound can beobtained, and concurrently (e.g., simultaneously) an offset effect thatthe sound pressure level of any one of the harmonic tones of the thirdsound becomes lower than (or less than) the sound pressure level of anyone of the harmonic tones of the first sound can be obtained. Therefore,it is possible to prevent or reduce the deterioration of sound qualityprovided to the user due to the harmonic tones of the first sound and toprovide a high-quality sound by increasing the sound pressure level ofthe fundamental tone of the first sound.

Further, according to the embodiment shown in FIG. 23, when the look-uptable 741 is used, the fundamental tone and harmonic tones of the secondsound can be determined, and circuit complexity can be lowered, comparedto when the phase shifter 750 is used.

FIG. 24 is a bottom view showing a display panel attached to the coverwindow of FIG. 2 according to an exemplary embodiment, and FIG. 25 is abottom view showing a bracket attached to the lower surface of thedisplay panel of FIG. 3 and a main circuit board disposed on the bracketaccording to an exemplary embodiment.

The embodiments shown in FIGS. 24 and 25 are different from theembodiments shown in FIGS. 3 and 4 in that the second sound generator520 is disposed on one surface of the display panel 300 instead of beingremoved from the bracket 600. In FIGS. 24 and 25, a descriptionsubstantially the same as the embodiment shown in FIGS. 3 and 4 may beomitted (e.g., may not be repeated).

Referring to FIGS. 24 and 25, the second sound generator 520 may beattached onto one surface of the display panel 300 using a secondadhesive member such as a pressure sensitive adhesive. As shown in FIG.24, when the panel lower member 400 is disposed on one surface of thedisplay panel 300, the second sound generator 520 may be attached ontothe panel lower member 400 through the second adhesive member.

The second sound generator 520 may be a piezoelectric element or apiezoelectric actuator that vibrates the display panel 300 using apiezoelectric material contracting and expanding according to an appliedvoltage. Although it is illustrated in FIG. 24 that the second soundgenerator 520 has a rectangular parallelepiped shape, the shape of thesecond sound generator 520 is not limited thereto. The first soundgenerator 510 may be disposed adjacent to the upper side of the displaypanel 300, and the second sound generator 520 may be disposed adjacentto the lower side of the display panel 300.

A third connector 317 and a second sound driver 760′ may be disposed onone surface of the display circuit board 310. The third connector 317may include an insertion portion connected to a connection terminalprovided at one end of a second flexible circuit board 580 (e.g., asecond flexible printed circuit board).

The connection terminal provided at one end of the second flexiblecircuit board 580 may be inserted into the insertion portion of thethird connector 317. The other end of the second flexible circuit board580 may be connected to the second sound generator 520. The secondflexible circuit board 580 may be a flexible printed circuit board or aflexible printed circuit (FPC).

When both the first sound generator 510 and the second sound generator520 are piezoelectric elements or piezoelectric actuators, it issuitable to output a sound of a high frequency band. When the secondsound generator 520 is a linear resonant actuator LRA, the first soundgenerator 510 outputs a first sound of a high-frequency band in thesecond sound mode, and the second sound generator 520 outputs a secondsound of a low-frequency band in the second sound mode. In contrast,when the second sound generator 520 is a piezoelectric element or apiezoelectric actuator, the first sound generator 510 may output a firststereo sound in the second sound mode, and the second sound generator520 may output a second stereo sound in the second sound mode. That is,the display device 10 may provide stereo sounds in the second soundmode.

Although certain exemplary embodiments and implementations have beendescribed herein, other embodiments and modifications will be apparentfrom this description. Accordingly, the inventive concepts are notlimited to such embodiments, but rather, encompass the broader scope ofthe appended claims and various obvious modifications and equivalentarrangements as would be apparent to a person of ordinary skill in theart.

What is claimed is:
 1. A display device, comprising: a display panel; afirst sound generator on a first surface of the display panel, the firstsound generator being configured to vibrate the display panel to outputa first sound; and a second sound generator for outputting a secondsound by vibration, wherein a third sound is a sum of the first soundand the second sound, and a sound pressure level of at least one ofharmonic tones of the third sound is less than a sound pressure level ofat least one of harmonic tones of the first sound, wherein a soundpressure level of a fundamental tone of the third sound is greater thana sound pressure level of a fundamental tone of the first sound, andwherein the sound pressure level of a first harmonic tone of theharmonic tones of the third sound is less than the sound pressure levelof a first harmonic tone of the harmonic tones of the first sound. 2.The display device of claim 1, wherein a difference between a phase ofat least one of the harmonic tones of the first sound and a phase of atleast one of harmonic tones of the second sound is less than −90° andmore than 90°.
 3. The display device of claim 2, wherein the soundpressure level of at least one harmonic tone of the first sound isdifferent from the sound pressure level of at least one harmonic tone ofthe second sound.
 4. The display device of claim 1, wherein a differencebetween a phase of the fundamental tone of the first sound and a phaseof the fundamental tone of the second sound is in a range from −90° to90°.
 5. The display device of claim 4, wherein the sound pressure levelof the fundamental tone of the first sound is different from the soundpressure level of the fundamental tone of the second sound.
 6. Thedisplay device of claim 1, wherein the sound pressure level of a secondharmonic tone of the third sound is less than the sound pressure levelof a second harmonic tone of the first sound.
 7. The display device ofclaim 6, wherein a difference between a phase of the first harmonic toneof the first sound and a phase of the first harmonic tone of the secondsound is less than −90° and more than 90°, and a difference between aphase of the second harmonic tone of the first sound and a phase of thesecond harmonic tone of the second sound is less than −90° and more than90°.
 8. The display device of claim 7, wherein the sound pressure levelof the first harmonic tone of the first sound is different from thesound pressure level of the first harmonic tone of the second sound, andthe sound pressure level of the second harmonic tone of the first soundis different from the sound pressure level of the second harmonic toneof the second sound.
 9. A display device, comprising: a display panel; afirst sound generator on a first surface of the display panel, the firstsound generator being configured to vibrate the display panel to outputa first sound; and a second sound generator for outputting a secondsound by vibration, wherein a third sound is a sum of the first soundand the second sound, and a sound pressure level of at least one ofharmonic tones of the third sound is less than a sound pressure level ofat least one of harmonic tones of the first sound, wherein the soundpressure level of a first harmonic tone of the harmonic tones of thethird sound is greater than the sound pressure level of a first harmonictone of the harmonic tones of the first sound, and wherein the soundpressure level of a second harmonic tone of the harmonic tones of thethird sound is less than the sound pressure level of a second harmonictone of the harmonic tones of the first sound.
 10. The display device ofclaim 9, wherein a difference between a phase of the first harmonic toneof the first sound and a phase of the first harmonic tone of the secondsound is in a range from −90° to 90°.
 11. The display device of claim 9,wherein a difference between a phase of the second harmonic tone of thefirst sound and a phase of the second harmonic tone of the second soundis less than −90° and more than 90°.
 12. The display device of claim 1,wherein each of the first sound generator and the second sound generatoris a piezoelectric element or a piezoelectric actuator comprising apiezoelectric material configured to contract and to expand according toan applied voltage.
 13. The display device of claim 12, wherein thesecond sound generator is on the first surface of the display panel, andis configured to vibrate the display panel to output the second sound.14. The display device of claim 1, further comprising: a bracket on thefirst surface of the display panel, wherein the second sound generatoris on a second surface of the bracket that is opposite to a firstsurface of the bracket facing the display panel.
 15. The display deviceof claim 14, wherein the first sound generator is a piezoelectricelement or a piezoelectric actuator comprising a piezoelectric materialconfigured to contract and expand according to an applied voltage, andthe second sound generator is a linear resonant actuator configured tovibrate the bracket by generating a magnetic force utilizing a voicecoil according to an applied voltage.
 16. The display device of claim 1,further comprising: a first sound driver configured to convert firstsound data into first sound signals and to output the first soundsignals to the first sound generator; a second sound driver configuredto convert second sound data into second sound signals and to output thesecond sound signals to the second sound generator; and a phase shifterconfigured to modulate second sound data and to output the second sounddata to the second sound driver to shift a phase of a fundamental toneof the second sound and a phase of at least one harmonic tone of thesecond sound.
 17. The display device of claim 16, further comprising: amain processor configured to output the first sound data to the firstsound driver and to output the second sound data to the phase shifter;and a main circuit board with the main processor, the second sounddriver, and the phase shifter.
 18. The display device of claim 16,further comprising: a display circuit board on the first surface of thedisplay panel, the first sound driver being located on the displaycircuit board.
 19. The display device of claim 18, wherein the phaseshifter and the first sound driver are formed as one integrated circuit.20. The display device of claim 1, further comprising: a first sounddriver configured to convert first sound data into first sound signalsand to output the first sound signals to the first sound generator; asecond sound driver configured to convert second sound data into secondsound signals and to output the second sound signals to the second soundgenerator; and a look-up table configured to store information about afundamental tone and at least one harmonic tone of the second soundaccording to frequencies of a fundamental tone and at least one harmonictone of the first sound.
 21. The display device of claim 20, furthercomprising: a main processor configured to output the first sound datato the first sound driver and to output the second sound data to a phaseshifter; and a main circuit board with the main processor, the secondsound driver, and the look-up table.
 22. A sound providing method of adisplay device, comprising: shifting a phase of a fundamental tone of afirst sound in a first sound mode to generate a fundamental tone of asecond sound; shifting a phase of at least one harmonic tone of thefirst sound in the first sound mode to generate at least one harmonictone of the second sound; outputting first sound data comprisinginformation about the fundamental tone of the first sound and the atleast one harmonic tone of the first sound in the first sound mode, andoutputting second sound data comprising information about thefundamental tone of the second sound and the at least one harmonic toneof the second sound in the first sound mode; generating first soundsignals according to the first sound data and outputting the first soundsignals to a first sound generator; and generating second sound signalsaccording to the second sound data and outputting the second soundsignals to a second sound generator, wherein a third sound is a sum ofthe first sound and the second sound, and a sound pressure level of atleast one of harmonic tones of the third sound is less than a soundpressure level of at least one of harmonic tones of the first sound, andwherein the sound pressure level of a first harmonic tone of theharmonic tones of the third sound is less than the sound pressure levelof a first harmonic tone of the harmonic tones of the first sound. 23.The method of claim 22, further comprising: shifting a phase of any oneharmonic tone of the second sound, having the same frequency as thefundamental tone of the first sound, in a second sound mode; andoutputting second sound data comprising information about thefundamental tone of the second sound and the any one phase-shiftedharmonic tone of the second sound in the second sound mode.
 24. Themethod of claim 22, further comprising: shifting a phase of any oneharmonic tone of the second sound, having the same frequency as thefundamental tone of the first sound, in a second sound mode; shifting aphase of another harmonic tone of the second sound, having the samefrequency as the any one harmonic tone of the first sound, in the secondsound mode; and outputting second sound data comprising informationabout the fundamental tone of the second sound, the any onephase-shifted harmonic tone of the second sound, and the anotherharmonic tone of the second sound in the second mode.